The verdict in three sentences
A custom B2B e-commerce portal in London costs GBP 45,000-130,000 over 14-22 weeks, while a Shopify Plus or BigCommerce B2B licence runs GBP 2,000-8,000 per month before integration. The real trade-off is not the entry price but the 3-year TCO and how far you need to customise account pricing, quotes and ERP sync. For a wholesaler with a complex catalogue, custom pays off the moment the SaaS forces costly workarounds or caps your pricing rules.
Custom vs SaaS licence: the 2026 costs
B2B imposes rules that B2C never sees: negotiated per-customer pricing, volume discounts, multi-buyer accounts, order approval, 30/60-day terms and real-time stock/ERP sync. These requirements push the bill up.
| Item | Custom (GBP) | SaaS B2B (GBP) |
|---|---|---|
| Initial build | 45,000 - 130,000 | 12,000 - 40,000 (integration) |
| Annual licence | 0 | 24,000 - 96,000 |
| Account pricing | Unlimited, native | Plan-dependent |
| Real-time ERP sync | Custom | Connector or API |
| Go-live time | 14 - 22 wks | 8 - 14 wks |
| Code ownership | Full | None |
A custom build avoids the recurring licence but front-loads the cost; SaaS smooths spend but makes it perpetual and rising with volume.
3-year TCO: the calculation that decides
Here is total cost of ownership over 36 months for a mid-size London wholesaler, hosting and maintenance included (estimate, 2026 order of magnitude).
| Scenario | Yr 1 (GBP) | Yr 2 (GBP) | Yr 3 (GBP) | 3-yr total |
|---|---|---|---|---|
| Custom (build 85,000) | 100,000 | 18,000 | 18,000 | 136,000 |
| Shopify Plus B2B | 60,000 | 60,000 | 66,000 | 186,000 |
| BigCommerce B2B | 44,000 | 44,000 | 48,000 | 136,000 |
Over three years, custom and BigCommerce converge around GBP 136,000, but custom removes any licence-increase risk and leaves a resellable asset. Beyond year 3 the gap widens in favour of custom.
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Mini case study
James, wholesale sales director at an industrial supplies distributor in London, manages 1,200 customer accounts with negotiated price lists. His reps still key in 40 % of orders by hand, about 18 hours a week at GBP 22/h, or GBP 20,592/year. By deploying a GBP 85,000 custom portal synced to his ERP, he cuts manual entry by 80 % (saving ~GBP 16,500/year) and sees a 30 % rise in reorder rate from self-service repurchasing. On GBP 2.4M of reorder revenue at 14 % margin, that +30 % is roughly GBP 100,000 of additional margin per year: the portal pays back in under 12 months.
FAQ
What does a B2B portal really cost in London in 2026? Budget GBP 45,000-130,000 custom depending on pricing-rule and integration complexity. A standard wholesaler project with ERP sync lands around GBP 80,000-95,000.
Is Shopify Plus B2B enough for real B2B? It covers account pricing, minimum quantities and deferred payment, but struggles with very complex pricing rules and multi-level approval workflows, where custom regains the edge.
What is the go-live timeline? 14-22 weeks custom, 8-14 weeks on a configured B2B SaaS, with ERP sync the longest task either way.
Is ERP sync included? Rarely as standard: budget GBP 12,000-30,000 for a connector or API integration, whether custom or SaaS.
When does custom become more profitable? As soon as the annual SaaS licence exceeds GBP 50,000-60,000 or forced workarounds create recurring operating costs; the tipping point usually sits between year 2 and year 3.
Let's scope your project. Tell us about your catalogue, account pricing rules and ERP: we cost build vs SaaS and the 3-year TCO. 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.
