Whether you plan to build a custom ERP or extend Odoo, ERPNext or SAP Business One, the cost is set by scope. This guide breaks down each driver so your operations and finance teams can shape the project before asking for an estimate. For our approach to the work itself, see ERP development and extension.
Why do ERP estimates vary so much?
ERP estimates vary because an ERP touches every department, and each company combines modules, entities and integrations differently. Two distributors of similar size can need very different systems if one runs three companies in two currencies with e-commerce and the other runs one entity with a single warehouse.
The way to get comparable estimates is to describe the same scope to every vendor: modules, entities, integrations, data and users.
What are the main cost drivers?
| Cost driver | Lower effort when… | Higher effort when… |
|---|---|---|
| Modules | One or two areas, such as inventory and purchasing | Full suite: sales, purchase, inventory, finance, HR, manufacturing, projects |
| Entities & currencies | One company, one currency | Several companies, inter-company flows, consolidation, multi-currency |
| Build vs extend | Platform covers most needs | Heavy changes in core modules, or fully custom |
| Integrations | Accounting export only | E-commerce, CRM, banks, payroll, devices, logistics, BI |
| Data migration | Clean masters and opening balances | Years of history, open documents, poor data quality |
| Users & roles | Few roles, one location | Segregation of duties, branch permissions, approval chains |
| Infrastructure & hosting | Standard cloud setup | Data residency, high availability, on-premise, disaster recovery |
| Compliance | Domestic invoicing only | E-invoicing mandates, audit requirements, industry rules |
| AI usage | None at first | Document extraction, forecasting, assistants (plus model usage) |
| Support | Business-hours retainer | Extended hours, month-end cover, frequent changes |
Modules and processes
Each module carries its own rules. Inventory with batches, serials, multiple warehouses and valuation methods is more involved than simple stock counts. Purchasing with approvals and three-way matching is more involved than simple purchase orders. Manufacturing and project accounting add another level.
Companies, branches and currencies
Multi-company setups need inter-company transactions, separate tax settings, consolidation and careful permissions. Multi-currency adds exchange-rate handling and revaluation. These requirements shape the data model, so they must be known up front.
Build or extend
Extending a platform means paying for the parts that differ from standard, plus any licences. Building custom means building everything, but exactly as needed. The Odoo vs custom ERP guide covers when each wins.
Integrations
Common ERP integrations include online stores, CRM, accounting packages, banks, payroll and biometric devices. Each integration needs mapping, error handling and monitoring. See ERP and e-commerce integration and accounting software integration.
Data migration
Migration covers masters (customers, suppliers, items, accounts), opening balances, open documents and, optionally, history. Every migration needs trial runs and reconciliation reports signed off by finance. Poor source data multiplies the effort.
Infrastructure, compliance and support
Hosting covers servers or cloud services, database, storage, backups and monitoring. E-invoicing mandates in the UAE, Saudi Arabia, Europe and elsewhere require structured invoices and a provider connection; see our e-invoicing integration pages. Support after go-live is essential for an ERP, especially through the first period closings.
Which costs continue after go-live?
- Hosting, storage, backups and monitoring.
- Platform licences, if you extend a licensed ERP.
- Third-party services: e-invoicing providers, payment gateways, logistics APIs.
- AI model usage for AI features.
- Support, updates and new requirements as the business changes.
How do you keep ERP cost under control?
- Phase the project. Go live module by module, starting where the pain is greatest.
- Standardise before you customise. Change a process to fit a standard module where the process is not a real advantage.
- Limit history. Migrate opening balances and open documents; archive older history in a read-only store.
- Design compliance in. Include e-invoicing and tax data from day one.
- Name process owners. A decision-maker per module prevents scope drift and rework.
Questions to ask before you start
- Which processes cause the most errors or delays today?
- How many companies, branches, warehouses and currencies must the ERP handle?
- Which processes are standard, and which are genuinely unique to us?
- Which systems must the ERP connect to, and which will it replace?
- How much data must move, and how clean is it?
- Which e-invoicing or tax mandates apply to us, and when?
- Who will own each module internally?
- What level of support do we need around month-end and year-end?
Get a scoped estimate
Every system is different. Send us your requirements and we’ll come back with a module-by-module scope, timeline and infrastructure plan. We reply within 1 business day.
Book a scoping call or message an engineer on WhatsApp, and read how we approach ERP development and extension.