25€? No. Maybe 5-10€ depending on how complex is the question and of course depending on the programming language. Of course the response time is essential, let's say within 1 hour( I could use a break and come back late with a solution). Maybe a subscription model or even credits is fine by me. The answer would be fiddle or written solution( there's your pricing model). Also I would like 2 independent answers like others said( with extra € ) Stack overflow is a good place but sometimes it takes too long( there is bounty of course you can't 'buy' more rep). Choosing who will answer it is also an option( maybe from which country, for various reasons) Nice idea, give it a go!