The verdict in three sentences
For a Berlin manufacturer managing 400 suppliers, the ERP supplier module (or SAP Ariba) is the fast option if your purchasing processes follow the standard and you have fewer than 150 active suppliers. Beyond that, per-supplier licences (30 to 90 EUR a year) and configuration limits make a custom extranet at 40,000 to 85,000 EUR more profitable from year three. Either way, the measurable goal is the same: recover 2 to 4 days a month of chasing, order acknowledgements and re-keying.
What each option costs in 2026
The purchasing director of a precision engineering company in Berlin-Spandau sums it up: 400 suppliers, 1,800 purchase orders a month, acknowledgements arriving as PDFs by email and re-keyed by hand into SAP. The two paths do not share the same cost structure.
| Item | ERP module / SAP Ariba | Custom extranet |
|---|---|---|
| Setup | 15,000 to 40,000 EUR (integrator) | 40,000 to 85,000 EUR |
| Annual licences | 30 to 90 EUR per supplier | 0 EUR (hosting 150 to 400 EUR per month) |
| Annual cost for 400 suppliers | 12,000 to 36,000 EUR | 1,800 to 4,800 EUR + maintenance |
| Ongoing development | Included in vendor licence | 15 to 20% of build per year |
| Time to go-live | 6 to 12 weeks | 12 to 18 weeks |
| Workflow customisation | Limited to configuration | Full |
| Supplier-side usability | Generic portal, often seen as heavy | Designed for small subcontractors |
The ERP module wins when the ERP is recent (SAP S/4HANA, Microsoft Dynamics 365) and the vendor offers a native portal. Custom takes the lead when your suppliers are small workshops in Saxony or Poland who refuse yet another portal and need a three-click journey.
Total cost over five years
What matters is cumulative cost, not entry price. Assumptions: 400 suppliers, average licence 55 EUR, custom extranet at 60,000 EUR with 18% annual maintenance.
| Year | ERP module (cumulative) | Custom extranet (cumulative) |
|---|---|---|
| Year 1 | 27,500 + 22,000 = 49,500 EUR | 60,000 + 3,000 = 63,000 EUR |
| Year 2 | 71,500 EUR | 76,800 EUR |
| Year 3 | 93,500 EUR | 90,600 EUR |
| Year 4 | 115,500 EUR | 104,400 EUR |
| Year 5 | 137,500 EUR | 118,200 EUR |
| 5-year gap | Baseline | 19,300 EUR saved |
The break-even comes around year three. With only 150 suppliers, the ERP module stays cheaper over five years (about 69,000 EUR versus 118,200 EUR). The number of active suppliers is the deciding variable.
The features that deliver the time savings
The 2 to 4 days recovered each month come from five specific features, to demand whichever option you pick.
| Feature | Estimated monthly gain | Complexity |
|---|---|---|
| One-click order acknowledgement | 1 to 1.5 days | Low |
| Supplier updates delivery dates | 0.5 to 1 day | Medium |
| Certificate upload (ISO 9001, material, REACH) with expiry alerts | 0.3 to 0.5 day | Low |
| Automatic reminders at D-3 and D+1 | 0.5 to 1 day | Low |
| Two-way ERP synchronisation | Eliminates re-keying | High |
ERP synchronisation often accounts for 30 to 40% of a custom extranet budget. Demand a documented connector with logging: when a sync fails, messages must be replayable without re-keying.
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Mini case study
Katrin, purchasing director of a 250-employee manufacturer in Berlin, has three buyers each spending 3 days a month chasing and re-keying, 9 days in total. At a loaded cost of 420 EUR per day, that is 45,360 EUR a year. With a custom extranet at 60,000 EUR, she targets a gain of 6 days a month: 72 days a year, or 30,240 EUR. Adding fewer stock-outs from unreported delays (estimated at 12,000 EUR a year), savings reach 42,240 EUR. Payback in roughly 17 months, maintenance included.
FAQ
From how many suppliers is a custom extranet worth it?
As a 2026 order of magnitude, beyond 250 to 300 active suppliers over a five-year horizon. Below that, the native ERP module is usually cheaper.
How long does a custom supplier extranet take?
Plan 12 to 18 weeks, including 4 to 6 for ERP synchronisation. Rolling out in waves of 50 suppliers keeps support to 2 or 3 days per wave.
Do suppliers pay to access the extranet?
Almost never: charging them slows adoption. With an ERP module, the per-supplier licence (30 to 90 EUR) stays with the buyer.
How do we get small suppliers to adopt it?
Passwordless secure links, a mobile interface and a 3-minute training video usually do the job. Aim for 80% adoption within six months.
Can the extranet handle tenders?
Yes, a sourcing module costs 12,000 to 25,000 EUR extra. It pays off beyond 30 tenders a year.
Let's scope your project. We compare an ERP module and a custom extranet based on your actual supplier count, with an indicative budget of 40,000 to 85,000 EUR and a 12 to 18 week plan. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
