The Hidden Cost of ERP Customisation on SAP and Oracle

SAP ABAP development costs $150–$300 per hour. Oracle PL/SQL customisation runs the same range. A mid-market manufacturer that needs SAP to handle a process it was not designed for — a custom approval workflow, a non-standard costing method, a reporting structure that crosses module boundaries — will spend $200,000–$500,000 on customisations. And the result is still a workaround, not a solution. It is SAP doing something SAP was not built to do.

The problem is not SAP or Oracle. Both are strong ERPs for the processes they were designed to handle. The problem is the assumption that every business process must live inside the ERP. Some should not.

Why does ERP customisation cost so much?

Three factors compound to make ERP customisation expensive:

Specialist labour costs. ABAP developers and SAP functional consultants charge $150–$300/hour because the talent pool is small and shrinking. Fewer developers are learning ABAP. The ones who know it well are in high demand. Oracle Forms and PL/SQL developers face the same supply constraint. A custom web application built in Python, Node.js, or .NET uses a developer pool that is 50–100x larger — which means lower hourly rates and faster hiring.

Upgrade brittleness. Every SAP customisation creates a potential upgrade conflict. When SAP releases a new version, every custom ABAP program, every modified transaction, and every custom report needs to be tested and potentially rewritten. Companies with heavy customisations routinely skip SAP upgrades for years because the upgrade cost exceeds the value of the new features. That deferred upgrade becomes technical debt that compounds — each skipped version makes the next upgrade harder.

Testing overhead. A change in one SAP module can cascade into others. Modifying the procurement workflow can affect inventory valuation, cost centre reporting, and financial closing. Every customisation requires cross-module regression testing. A standalone custom application that integrates with SAP via APIs only needs to test its own logic plus the API contract — not the entire ERP.

What kinds of processes should not live inside the ERP?

The ERP should own financials, inventory, production planning, and standard procurement. Those are the processes SAP and Oracle were designed for, and they do them well. The processes that should not live inside the ERP are the ones where the business logic is unique to your company:

• Custom cost estimation — the costing model uses proprietary formulas that do not fit the ERP's standard costing methods. Building a custom estimator that writes results back to the ERP costs less than modifying the ERP's costing module.
• Complex approval workflows — conditional routing based on variables the ERP does not track (project phase, external compliance status, cross-departmental dependencies). A dedicated workflow application handles this and pushes approved transactions to the ERP.
• Customer-facing portals — vendor portals, customer order tracking, supplier qualification workflows. These need modern UX, mobile access, and role-based permissions that SAP GUI and Oracle Forms cannot deliver without a complete front-end rebuild.
• Quality and compliance tracking — inspection workflows, non-conformance reports, corrective action tracking, and audit documentation. The ERP records the outcome. The process of getting to that outcome needs its own system.
• Operational dashboards and reporting — cross-module reports that combine data from procurement, production, quality, and finance. SAP BW and Crystal Reports can do this, but the development cost and maintenance burden often exceed a custom dashboard that pulls data from the ERP via APIs.

What does the custom-module-plus-ERP architecture look like?

The architecture is straightforward: the ERP stays as the system of record for financial and inventory data. Custom applications handle the processes that do not fit. The two communicate through APIs or an integration layer.

In practice, this means: a custom procurement approval system sends approved POs to SAP. A custom cost estimator writes standard cost records to SAP after the estimate is complete. A customer portal reads order status from SAP and displays it in a modern interface. The ERP does what it does well. The custom applications handle everything else.

Madgeek built exactly this architecture for Tejas Networks — a publicly listed company whose procurement workflow had outgrown what SAP could handle without extensive customisation. Instead of modifying SAP, we built a custom procurement platform that encoded Tejas's actual approval rules and integrated with their existing ERP. The result: 90% reduction in paper-based approvals, a complete digital audit trail, and an ERP that stayed clean and upgradeable.

When is the custom module cheaper than ERP customisation?

Run the numbers. A custom application that handles one complex business process costs $50,000–$120,000 to build, with $2,000–$4,000/month in ongoing support. It uses standard web development talent at $50–$100/hour. It does not create ERP upgrade conflicts. It can be modified independently of the ERP release cycle.

The same scope in SAP ABAP: $100,000–$300,000 in development at $150–$300/hour. Plus $20,000–50,000 in regression testing. Plus an unknown future cost every time SAP releases an upgrade. Plus the opportunity cost of the SAP team spending months on a customisation instead of other projects.

The custom module is cheaper when: the process does not need real-time, bidirectional ERP integration (most do not — they need to read from and write to the ERP, not live inside it), the business logic is unique enough that the ERP's configuration tools cannot handle it without code, and the company plans to stay on the ERP for 5+ years (meaning every customisation creates 5+ years of upgrade risk).

For a detailed comparison of custom ERP modules versus SAP/Oracle for manufacturing, see the manufacturing software gap map. For the full Tejas Networks case study, see how we replaced paper-based procurement with a custom platform. Madgeek's custom ERP development service covers this type of build.