The verdict in three sentences
Migrating a packaged B2B store to custom is not a technical whim: you do it when the platform throttles growth. In 2026 in Amsterdam, budget 8,000 to 20,000 EUR for catalogue and customer migration, plus 45,000 to 90,000 EUR of rebuild, over 5 to 9 months. The trigger arrives beyond 2,000 SKUs or when ERP integration becomes impossible on the current solution.
Spotting the tipping point
A SaaS ceiling shows up not in the price but in daily blockers. Here are the 2026 signals that justify a migration.
| Ceiling signal | Packaged SaaS | Real need |
|---|---|---|
| Number of SKUs | Slow above 2,000 | 5,000-30,000 smooth |
| Pricing rules | 2-3 tiers | Unlimited per-customer grids |
| ERP integration | Nightly CSV export | Real-time sync |
| Approval workflow | Absent | Multi-level |
| Catalogue performance | Slow filters | Instant search |
| Add-on cost | +100-400 EUR/month per module | Included in core |
As soon as three of these signals turn red, the hidden cost of SaaS (add-on modules, manual workarounds, lost sales) exceeds a custom build amortised over 3 years.
What the migration really costs
Migration breaks into two blocks: data migration and rebuild. Here is the typical split of a 70,000 EUR Amsterdam project.
| Line item | Indicative amount | Timeline |
|---|---|---|
| Audit and data mapping | 5,000 EUR | 2-3 weeks |
| Catalogue migration (2,000+ SKUs) | 9,000 EUR | 4-6 weeks |
| Account and history migration | 6,000 EUR | 3-4 weeks |
| Front-end + order flow rebuild | 28,000 EUR | 10-14 weeks |
| Real-time ERP integration | 16,000 EUR | 6-10 weeks |
| Testing, SEO, DNS switchover | 6,000 EUR | 3-4 weeks |
The number-one migration risk is losing search rankings: keep URLs or set systematic 301 redirects to avoid a 20-40% traffic drop.
How to secure the switchover
A failed migration often costs more than the project itself, between lost traffic and blocked orders. Here is the 2026 checklist of points to lock down before go-live.
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| Control point | Risk if neglected | Cost avoided |
|---|---|---|
| 301 redirect plan | -20 to -40% traffic | 5,000-15,000 EUR revenue/month |
| Faithful customer-price migration | Billing disputes | 1,500-2,000 EUR/month |
| Dual operation 2-3 weeks | Order outage | Customer loss |
| Testing on key accounts | Buyer blocking | Churn |
| Full backup before switch | Data loss | Irreplaceable |
| Internal team training | Under-use | Delayed ROI |
The most profitable advice: never cut the old platform on the same day. Run both in parallel for two to three weeks, long enough to confirm 100% of orders pass correctly on the new core. This overlap costs 2,000 to 4,000 EUR, but it avoids the disaster scenario of order intake going dark in peak season.
Mini case study
Sophie, head of a hospitality equipment wholesaler in Amsterdam, is capped at 2,400 SKUs on a packaged solution billed at 950 EUR/month, plus 600 EUR/month of add-ons. Each nightly ERP sync causes stock errors costing about 1,800 EUR/month in disputes and credit notes. She migrates to custom at 70,000 EUR. By removing add-ons (1,550 EUR/month, i.e. 18,600 EUR/year) and stock disputes (21,600 EUR/year), she saves about 40,000 EUR/year: the migration pays back in under 21 months, before counting the sales upside of a wider catalogue.
FAQ
At how many SKUs should you migrate? The 2026 practical threshold sits around 2,000 SKUs: beyond that, most packaged solutions slow down on filters and sync. With a 5,000+ SKU catalogue, custom becomes almost unavoidable.
How long does a B2B migration take? Budget 5 to 9 months depending on data volume and ERP complexity. Catalogue and customer migration alone accounts for 8 to 12 weeks.
Will we lose our Google rankings? Not if you set 301 redirects on every old URL. Without a redirect plan, a migration drops organic traffic 20-40% for 2 to 4 months.
Can we migrate without interrupting orders? Yes, with a phased switch: old and new run in parallel for 2 to 3 weeks. This dual operation costs about 2,000 to 4,000 EUR.
Is custom more expensive over time? No: over 3 years, custom maintenance (6,000-14,000 EUR/year) is often below the licences + modules of an advanced SaaS (15,000-30,000 EUR/year).
Let's scope your project. Send us your SKU volume, your ERP and your current blockers: we cost the migration and rebuild. 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.