The verdict in three sentences
For a 200 employee manufacturer doing 6 million EUR a year, roughly 5.1 million GBP, on an ageing Magento store, the question is not whether to migrate but where to: Shopify Plus, from 2,300 USD a month plus 0.15 to 0.25% of volume, or a custom platform. Shopify Plus wins when the catalogue and B2B rules stay standard; custom wins once pricing, product configuration or ERP integration leave the box. Either way, a replatforming project of 50,000 to 170,000 GBP in the UK market only pays off if it preserves search rankings and customer accounts from day one.
Why an ageing Magento keeps getting more expensive
A Magento 2 store installed six or seven years ago, never upgraded to a recent major version, piles up abandoned third party extensions, late security patches and oversized hosting. Hidden costs eventually exceed those of a migration.
| Annual cost (order of magnitude 2026) | Ageing Magento | Shopify Plus | Modern custom build |
|---|---|---|---|
| Licence or subscription | 0 GBP (Open Source) to 35,000+ GBP (Adobe Commerce) | 2,300 USD a month minimum, about 22,000 GBP a year | 0 GBP |
| Volume fees (5.1 M GBP) | 0 GBP | 0.15 to 0.25%, or 7,700 to 12,800 GBP | 0 GBP excluding payment fees |
| Hosting and managed services | 10,000 to 25,000 GBP | Included | 2,500 to 10,000 GBP |
| Maintenance and security updates | 22,000 to 50,000 GBP | 4,000 to 13,000 GBP (apps, tweaks) | 7,000 to 21,000 GBP |
| Third party apps or extensions | 4,000 to 13,000 GBP | 5,000 to 17,000 GBP | Built once |
| Indicative annual total | 36,000 to 123,000 GBP | 39,000 to 64,000 GBP | 9,500 to 31,000 GBP |
These totals exclude the initial rebuild. They show that Shopify Plus recurring cost is predictable but grows with revenue, while custom requires an upfront investment that depends more on scope.
Shopify Plus or custom: the B2B decision grid
Since 2023 Shopify Plus has offered native B2B: companies, locations, catalogues and price lists per customer, net 30 or 60 terms, minimum quantities. That is enough for many manufacturers. Limits show up with product configurators, prices calculated live by the ERP, negotiated quotes and catalogues of tens of thousands of SKUs with multiple variants.
| Criterion | Shopify Plus B2B | Custom build |
|---|---|---|
| Catalogue up to 20,000 SKUs, simple variants | Very good fit | Good fit |
| ERP calculated prices on every cart | Possible via app, watch latency | Native |
| Complex product configurator (sizes, options) | Limited, third party app | Native |
| Negotiated quote converted to order | Partial | Native |
| Time to launch | 3 to 6 months | 4 to 8 months |
| Vendor lock in | High | Low, you own the code |
| Rebuild cost (UK market, order of magnitude 2026) | 50,000 to 120,000 GBP | 70,000 to 170,000 GBP |
At Kolonell, a custom B2B e-commerce platform sits in the applications grid: medium, 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR), or complex, 7,000,000 to 15,000,000+ FCFA (10,670 to 22,870+ EUR) for a manufacturer this size with ERP and configurator. Data migration, specific connectors and hosting are priced in the quote.
Preserving SEO and customer accounts: the migration plan
A botched migration commonly loses 20 to 40% of organic traffic for three to six months. The rules are well known:
- inventory every indexed URL that drove traffic over 12 months;
- line by line 301 redirect map, tested before cutover;
- carry over title tags, descriptions and product and category content;
- migrate customer accounts with order history; hashed passwords are not always transferable, so plan a reset email at launch;
- carry over B2B price lists, delivery addresses and payment terms;
- monitor Search Console daily for 8 weeks after go live.
Mini case study
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James, e-commerce director of a 200 employee commercial furniture manufacturer near London, does 5.1 million GBP a year online. His Magento costs him about 80,000 GBP a year (hosting, maintenance, extensions).
Shopify Plus option: rebuild at 95,000 GBP, then about 22,000 GBP subscription, 10,000 GBP volume fees and 13,000 GBP of apps and tweaks, or 45,000 GBP a year. Annual saving: 35,000 GBP, payback in 2.7 years. Custom option: higher rebuild cost but recurring cost around 21,000 GBP a year, a saving of 59,000 GBP a year. If custom costs less than 159,000 GBP, it breaks even within 2.7 years, with code ownership and uncompromised pricing rules on top. The final choice therefore depends on B2B rule complexity, not budget alone.
FAQ
Can we migrate without losing Google rankings?
Yes, if every important URL is 301 redirected and content is carried over. A temporary 5 to 10% dip for a few weeks is common; a 30% drop signals an incomplete redirect map.
What does Shopify Plus cost at 5.1 million GBP revenue?
Count about 2,300 USD a month minimum subscription plus 0.15 to 0.25% of volume, or roughly 29,000 to 35,000 GBP a year before apps and payment fees.
Will B2B customers have to recreate their accounts?
No, accounts, addresses and history migrate. Passwords often require a reset: a clear email sent at launch limits calls to customer service.
How long does a migration take?
Plan 3 to 6 months for Shopify Plus and 4 to 8 months for custom, including 4 weeks of testing and a cutover outside peak season.
Can we keep Magento and modernise it?
Yes, with a version upgrade and extension cleanup, for 25,000 to 70,000 GBP. It postpones the decision by 2 to 3 years without lastingly cutting maintenance costs.
Let's scope your project. Magento audit, Shopify Plus versus custom choice, redirect map and B2B account migration: we scope the replatforming and its cutover schedule. 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.
