The feature itself is often an afternoon
If you need an extra box on the product page where the customer picks a colour, and the choice has to travel with the order, then that code is straightforward. If that were all, the price would be too.
But a plugin lives in an installation that gets updated, used by people who do unexpected things, and looked after by someone who was not there when it was built. That is what costs.
It is the edges that take the time
What happens if the field is empty? If someone types an emoji into it? If two employees edit the same order at once? Who may see the button, and who may press it? What does it say in English? What happens when the customer changes their mind after paying?
Each of those questions is small. Together they are usually bigger than the feature itself. A quote that does not mention them has either answered them out of sight or deferred them to you.
Three free plugins are rarely free
The ordinary route is to find three plugins that each solve a third and get them to work together. Sometimes that is the right call, and then we say so.
But the price is simply paid later. The three update on their own schedules, and updating one can break another. None of them was built for your workflow, so staff learn to click around what is missing. And when something goes wrong, nobody owns the fault. A bespoke thing that does exactly the one thing you need is often less code to own than three half solutions.
What makes a plugin expensive to own
Four things, again and again: that it is welded to the theme, so you cannot change the design without a rebuild. That it uses extension points which disappear at the next major update. That there is not a single test, so nobody dares touch it. And that only one person knows how it works.
None of those four cost anything on the day the code is delivered. They cost the whole amount three years later, when somebody has to go in and change a detail and ends up rebuilding it from scratch.
Ask this before you say yes
Ask what happens at the next major platform update, and who pays for the adjustment. Ask whether the code can be taken over by someone else — and ask to see what is actually in that documentation. Ask whether there are tests, and what they cover.
And ask what has deliberately been left out. A quote where everything is included is either not thought through or not fully priced. We would rather write down what we are not building than leave it open.
In short
- The feature is rarely the expensive part. The edges — permissions, error states, language, concurrency — are.
- Three plugins fighting each other cost nothing at purchase. They cost at every update.
- Welded to the theme, vanished extension points, no tests, and one person with the knowledge are the four expensive things to own.
- Ask to see what has deliberately been left out. A quote with no exclusions is not finished thinking.