Ask three agencies to quote for the same online store and you might get £2,000, £9,000 and £30,000. That spread isn't dishonesty — it reflects genuinely different builds hiding behind the same words. Without knowing what drives the number, it's almost impossible to brief sensibly or spot a fair price. Let's make the costs concrete.
The main price bands
UK ecommerce builds in 2026 tend to fall into three rough tiers:
| Tier | Typical cost | What you get |
|---|---|---|
| DIY / template | £0–£1,500 | You build it yourself on a paid theme |
| Professional build | £3,000–£12,000 | Agency-built store, custom design, key integrations |
| Custom / complex | £15,000–£60,000+ | Bespoke features, large catalogue, deep integrations |
What actually drives the price
Five factors do most of the work in any quote. Design — a custom-designed shop costs more than a configured theme. Catalogue size — uploading and structuring thousands of products takes real hours. Integrations — connecting accounting, ERP, fulfilment or CRM systems adds cost fast. Custom features — subscriptions, bundles, configurators and unusual checkout logic all push the number up. And migration — moving from an existing store adds work to protect data and rankings.
If you're choosing between platforms, our Shopify vs WooCommerce comparison explains how each affects both build and running costs.
Don't forget the ongoing costs
The build price is only part of the story. Every store carries monthly running costs that owners routinely underestimate:
- Platform or hosting: £20–£290 a month depending on choice.
- Payment processing: typically 1.4%–2.9% plus a small fixed fee per transaction.
- Apps and plugins: £40–£150 a month for reviews, email, subscriptions and the like.
- Maintenance: updates, security and small fixes — either your time or a retainer.
For a typical small store, expect £50 to £300 a month all in. Plan for it from day one so the running costs don't eat your early margins.
Where DIY makes sense — and where it doesn't
Building it yourself is a reasonable way to test an idea cheaply. If you have time and patience, a tidy starter shop is achievable for the price of a theme and a domain. The risk is the hidden cost of your own hours and the rework that often follows when a DIY store hits its limits.
Once sales justify it, professional help pays for itself through better conversion, faster pages and fewer headaches. A good ecommerce developer will also stop you over-spending on features you don't yet need.
How to brief for an accurate quote
Vague briefs produce vague quotes. To get comparable numbers, tell each agency your catalogue size, the integrations you need, whether you're migrating, and your must-have features versus nice-to-haves. The clearer your brief, the tighter and more honest the quotes.
Ready to get real numbers for your project? Shortlist two or three vetted UK studios from our ecommerce developers directory, send them the same brief, and compare like for like before you decide.