Building an ecommerce site: hosted platform or custom build
There are three ways to build an ecommerce store, and your revenue decides which one is right. The hidden costs, the crossover point, and what replatforming actually costs.
The honest answer to “what does it cost to build an ecommerce site?” starts by changing the question. There are three distinct routes and their costs are not even on the same scale — one is a few hundred dollars a month, another is a six-figure project budget.
The real question is: at this revenue, which cost structure is cheaper?
Three routes, three cost structures
Marketplaces (Amazon, Trendyol, Etsy). Setup cost is close to zero. In exchange you pay commission on every sale and the customer belongs to the marketplace, not to you. No email list, no remarketing, no brand story.
Hosted platforms (Shopify, BigCommerce, and local equivalents). You pay rent and the infrastructure is not your problem. It launches fast — genuinely a matter of days. The ceiling starts wherever the platform’s model ends.
A custom build. Written from scratch, entirely yours. The highest starting cost and the lowest unit cost — but only past a certain scale.
The visible cost and the invisible one
On hosted platforms, the advertised monthly fee is usually half of what you will actually pay. The real invoice adds up like this:
- Plan fee — the fixed monthly line.
- Transaction fee — an extra cut per sale if you don’t use the platform’s own payment rails.
- Payment processor commission — a separate agreement with your bank or PSP, tiered by volume.
- App subscriptions — shipping, accounting, reviews, email. Five to ten apps a month will quietly exceed the plan fee.
- Theme and customisation — the theme is a one-off, but every “can we make it do this” is developer hours.
Add those up and the hosted platform’s monthly cost grows with revenue. A custom build’s cost does not — beyond the server bill it stays flat. The two curves cross somewhere.
That crossing usually lands here: when monthly revenue reaches the point where commissions alone would fund a development team, and order volume makes operational automation mandatory. Below it, a hosted platform is almost always the right answer.
When a hosted platform is the correct call
If two of these three are true, don’t open the custom software discussion:
- Your catalogue is standard — size, colour, stock. No configurators, subscriptions, or B2B price lists.
- You haven’t validated product-market fit yet. If you don’t know which product sells, there is no sense financing that uncertainty with expensive infrastructure.
- You have no technical team and no plan to build one.
In that situation the money belongs in traffic and conversion, not infrastructure. As we covered in the ecommerce conversion rate piece, every percentage point lost in the cart costs far more than the platform decision does.
When a custom build is genuinely warranted
The reason to move is never “it would look nicer.” It is one of these:
- The platform’s model doesn’t fit your business. Subscriptions, rentals, made-to-measure, dealer pricing, multi-warehouse stock. You can bolt these on with apps, but every app is a failure point.
- Integration load has become heavy. ERP, accounting, warehouse, shipping, and marketplace sync all running at once — and orders drop when one of them breaks.
- Commission has overtaken development cost. When annual commissions plus app subscriptions approach the annual cost of a team, the maths has already made the decision.
- Speed became competitive. App-laden hosted themes are heavy, and past a certain revenue site speed is a measurable revenue line, not a vanity metric.
What replatforming actually costs
This is the most underestimated item on the list. Migration is not “let’s move the products across”:
- URL structure changes. If your product pages rank and you don’t build a complete 301 redirect map, those rankings reset. It is the most expensive ecommerce mistake we see.
- Customer passwords cannot be migrated. They are stored irreversibly by design, so every customer has to reset. That is measurable churn.
- Order history and returns — if they don’t come across, accounting and support work out of two systems for months.
Which is why URL structure and data model should be built to be portable even on day one. The addressing decisions we describe in the technical SEO guide are free if you make them at the start and ruinous three years later.
The legal line items people skip
Independent of platform, and jurisdiction-specific — in Türkiye these are mandatory:
- ETBİS registration. Registration with the national ecommerce information system, with the verification badge visible on the site.
- Distance selling agreement and pre-information form, confirmed in the order flow and retained.
- Returns and delivery terms, reachable before purchase.
- Privacy notice and cookie consent. If you run advertising pixels, they must not fire before consent.
These are not only a compliance matter. They are the first thing ad account reviews and payment provider applications look at — and if they are missing, your ad delivery stops.
A short checklist before you decide
Answer these four in writing:
- How many monthly orders do I expect over the next twelve months?
- Is my product model standard, or does it need configuration, subscriptions, or B2B pricing?
- Which systems must it talk to — accounting, ERP, warehouse, marketplaces?
- Who technically owns the site?
The fourth is the one that matters most. On a hosted platform the answer is “the platform”; on a custom build it is “you.” In that second case, make sure the repository, documentation and infrastructure access are genuinely in your name — it is your only protection the day you change agencies.
If you sell to dealers and business buyers, the requirements change: B2B e-commerce and dealer portals.
For the cost side in a broader frame, our website cost breakdown separates it line by line.
