I agree with most people here, just leave as soon as you can. This is a war you can't win but have several ways to "loose".

You could have the user to make a choice at start with buttons like office and gaming.

You mean a bit like https://choosemypc.net/ does? I'll be frank, I don't see it fitting in. For one, every complication of the UI of the site makes it more difficult to use (and I'm a big fan of keeping it as simple as possible). Second, I'm not sure you can reliably recommend a good office PC. Does that mean only going with an integrated gpu? Or do you even just need a slow cpu? A SSD certainly is not needed, is it, and what about a big HDD?

My impression is that while the initial reflex is to say yes to all of the above, in many cases at least one of the responses is no. When there is a lots of space needed, or when browsing needs a real fast processor (it indeed does for many pages and current browsers), or the R7 250 requested before (which is still a lot more than the integrated graphics of an haswell i3), and so on.

I still appreciate the suggestion, and if I see a way to built it in I'll certainly do it.

It might be nice to just have sliders to add a 'weight' to different components, maybe hidden behind an 'advanced' option .

That would be possible, as there is already a weight for the gpu. Thanks, I'll try it out.

Spread out one time licenses costs and VPS and domain. Rought 40USD/Month

It is also a bit tricky to count. Would I have bought as good computer if I wouldn't spend so much time coding on it etc.