Custom ERP Development Cost: Modules, Integrations and Rollout
On this page
Full custom software projects at Horizon Dynamics start at USD 50,000. For an ERP, the useful budget question is which operational process the first release will take responsibility for. Replacing order spreadsheets is a different scope from replacing financial accounting, procurement, manufacturing planning and warehouse operations together.
This guide uses an illustrative distributor to show how module costs fit into a larger estimate. The figures come from our Solution Studio model, not an industry price survey or a client invoice. For the general method of comparing estimates, read the software development cost guide.
Set the boundary: operations, accounting and existing tools
Our example distributor needs to accept an order, reserve stock, follow dispatch and see invoice status. The existing accounting system stays in place. The new operational system owns accepted orders and their progress; a warehouse system remains the stock source during the pilot. Accounting owns posted financial entries and payment records.
Before moving stock ownership into the new system, agree the cutover point and reconciliation checks. Two systems must not independently reserve the same available quantity without a defined coordination rule.
In this example, an invoice module provides an operational invoice view. It does not promise a general ledger, statutory reporting, country-specific tax treatment or currency revaluation. If any of those belong in the project, describe and estimate them explicitly. An accounting interface also needs its own scope, even when both systems have APIs.
Compare two operational ERP module scopes
The first configuration combines customer records, users, orders, stock, invoices, reporting and data transfer. The second enables the model's multiple-warehouse and multiple-currency options. It illustrates the incremental scope, without implying that every warehouse or currency rule has been specified.
Planning examples in USD, calculated with the current Solution Studio model. These are module estimates, not complete project quotations.
Orders, stock and invoice visibility
| Scope | Example budget |
|---|---|
| Shared foundation | $10,800–$16,200 |
| Users & roles | $5,400–$9,000 |
| Clients & CRM | $10,800–$16,200 |
| Orders | $8,100–$13,500 |
| Inventory | $9,900–$16,200 |
| Invoices | $6,300–$10,800 |
| Reports | $9,900–$16,200 |
| Data migration & sync | $8,100–$14,400 |
| Module estimate total | $69,300–$112,500 |
The same scope with warehouse and currency options
| Scope | Example budget |
|---|---|
| Shared foundation | $10,800–$16,200 |
| Users & roles | $5,400–$9,000 |
| Clients & CRM | $10,800–$16,200 |
| Orders | $8,100–$13,500 |
| Inventory | $13,500–$22,500 |
| Invoices | $9,000–$15,300 |
| Reports | $9,900–$16,200 |
| Data migration & sync | $8,100–$14,400 |
| Module estimate total | $75,600–$123,300 |
Included scope options: Multiple warehouses, Multiple currencies.
Open in Solution StudioShared foundation and required modules are counted once. Connections add no cost in this model. Discovery, detailed design, source-specific integrations, data cleanup, release validation and rollout are scoped separately. Hosting, licences, paid APIs, taxes and ongoing support are excluded.
The model uses estimated module hours and an illustrative rate of USD 45 per hour. Before using the range in a project budget, check the assumed workflows against your warehouse and accounting requirements.
The currency option requires further decisions: where exchange rates come from, when they are fixed and what happens after an order amendment. The warehouse option requires rules for reservations, transfers and availability. These details can change the eventual estimate beyond the model's allowance.
Budget the connections around their failure paths
For an order-to-accounting connection, specify the order identifier, posting trigger, required fields, acknowledgement and source of the returned status. Decide what happens when an order changes after posting. A retry should not create another financial document.
Ask for an estimate that names:
- Access and sandbox setup, mapping and test records for each external system.
- Duplicate handling, rejected records, retries and responsibility for unresolved exchanges.
- Reconciliation between the operational order and the corresponding accounting record.
- Monitoring, credentials management and behaviour when the external service is unavailable.
Reconcile these tasks with the generic data-transfer allowance in the module estimate. Assign each task once and identify any client-owned work. Without that step, two proposals containing “ERP integration” may describe substantially different deliveries.
Make the first release pass a concrete operational check
Use a small, synthetic example before working through production data. Suppose the pilot warehouse has ten available units of one item. An accepted order requests four. Under the agreed rule, the reservation leaves six available and four reserved. Cancelling before dispatch releases the reservation, returning availability to ten.
The release check should also show that:
- Repeating the same reservation event does not reserve another four units.
- A second order requesting seven units is rejected or routed to the agreed shortage workflow while the first reservation remains active.
- A cancelled order disappears from the open-order report but remains in the audit history.
- A failed accounting exchange remains visible for reconciliation; retrying the same request does not create a duplicate document.
Extend these acceptance scenarios to cover partial shipments, backorders and returns. Agree how each affects quantities, then include the implementation and tests in the estimate.
Estimate rollout as work, not a launch date
A first release can begin with one operating team or warehouse. Agree which records move, which history remains accessible in the old system and which process is authoritative during the pilot. Budget a migration rehearsal, staff walkthroughs, discrepancy review and a go/no-go decision.
Define a fallback before cutover. Returning to the old application is not enough if new orders have already been accepted: the recovery plan must account for those changes. The migration planning guide explains reconciliation and transition responsibilities.
Expansion to another warehouse should follow acceptance of the first workflow and assessment of local differences. Procurement, forecasting, manufacturing and additional legal entities can be separately scoped releases. Do not infer their cost from the size of the first release alone.
Use the phased ERP rollout guide and acceptance sheet to turn that release boundary into a pilot decision with named owners and evidence.
Keep reporting and operating costs visible
An overdue-order report and a financial revenue report answer different questions. Name the source, timestamp and definition for each measure. A dispatched order is not automatically a paid invoice. Use the reporting definition template to agree the meaning before pricing the dashboard.
For a complete budget, combine modules with assessment, design, source-specific integrations, cleanup, validation and rollout. Then state the operating period and add hosting, licences, paid APIs and support. Our build and twelve-month operating example demonstrates that separation; its allowances must be replaced with project-specific assumptions.
Horizon Dynamics provides ongoing project support through an agreed paid arrangement. Coverage, response expectations and team composition are scoped for the system's operation. Warranty defects and new functionality are separate from routine support. The Pricing & Process page describes hourly-team and fixed-module engagement models.
Decide what deserves custom development
If your core requirement is standard financial accounting, evaluate an established accounting product and the surrounding integrations before commissioning a replacement. Custom operational software may still be useful where your fulfilment rules, exceptions and cross-system coordination are distinctive.
Review our custom ERP development approach, then share the first operational process to improve. Include current systems, stock ownership, an example order and the business owner who can accept the release. Those details make an architecture discussion and subsequent estimate far more useful than a request for “a complete ERP”.
Related project experience.
Global Business Assistant
Orders, inventory and multi-currency accounting in a connected ERP and CRM.
Explore