ERP too heavy: building only the modules you need

Many mid-sized companies have an ERP they use 20% of: a few truly useful modules, and the rest weighing down screens, training and the bill. Others hesitate to roll one out, fearing two years spent adapting their organization to the software. There is a third way: build only the modules you need. Here is what it costs, how to compare it honestly with an off-the-shelf ERP, and when it is not the right choice.

What an off-the-shelf ERP costs

Public ERP prices are rare. As a benchmark, Microsoft publishes prices for Dynamics 365 Business Central. Prices checked in October 2026 on Microsoft’s French Business Central pricing page, per user per month, billed annually:

Microsoft states that these prices are indicative and directs buyers to its partners for purchase and deployment. Implementation costs are not public. Odoo also publishes a per-user price list on its website, which I could not reliably access when checking: verify it directly. Other vendors only share pricing on request.

The 3-year cost compared with custom software

An illustrative example, with assumptions to replace with your own: 25 users, including 12 full users on Essentials and 13 occasional users on Team Members, no price change over 3 years. The off-the-shelf implementation cost is a made-up amount of $22,400 (€20,000)excl. VAT, since there is no public price. For the custom option: an ERP limited to three modules (orders, inventory, production) at $39,200 (€35,000)excl. VAT, within my $16,800 to $56,000 (€15,000–€50,000)excl. VAT range, plus €5,000 a year for hosting and maintenance.

In this scenario, both options are roughly equal over 3 years. That is a common result, and a useful one: it shows that price should not decide on its own. Off-the-shelf licenses grow with every full user you add; custom software mostly costs money with each new feature. The full method is in the 3-year total cost.

Building only the modules you need

The logic is simple: keep off-the-shelf software where it is unbeatable, and build the operational core that sets you apart.

Each module is a delivered and tested batch. The first one solves the most expensive problem; the next ones come once the first is adopted. Connection details are covered in connecting your online store to your ERP.

When an off-the-shelf ERP is still the best choice

I would recommend an off-the-shelf ERP if:

• your processes are close to your industry’s standards: the ERP already covers them, tested by thousands of companies;
• you need many modules (finance, purchasing, sales, inventory, production, HR) from day one: building all of that would cost far more than $56,000 (€50,000)excl. VAT;
• your group mandates an ERP for consolidation;
• you want a long-standing vendor with a roadmap and a partner network;
• you have nobody internally to own scoping and acceptance testing.

Custom software makes sense when you use a small part of an ERP, when your processes are your competitive advantage, or when adapting a standard ERP costs more than building. The page on customizing Odoo or building custom software covers that last case.

Custom ERP price ranges

These ranges come from my public pricing. Multipliers apply depending on the number of users (×1.1 from 10 to 50, ×1.2 above). As a benchmark for the scale of a multi-portal platform, Nooxup V2, delivered, runs on 68 PostgreSQL tables. For your case, the estimator gives you a range in one minute.

Where to start

1. List the modules you actually use in your current ERP, or the ones you would need.
2. Identify the most expensive process in terms of re-entry, errors or delays.
3. Ask an off-the-shelf ERP partner for a complete quote: licenses, implementation, training, maintenance.
4. A 30-minute call, then scoping (1 to 2 weeks) for a fixed quote on the first module.
5. Mockups, development in batches, go-live, with data migration and three months of support included.