Hi edina! I can only give you my honest opinion, because it�s for Victor to decide.
For me, one of the things that makes this site sooooo special is "True sharing" - meaning that you "GIVE" and "TAKE". We all know that our profession is very demanding and we are all very busy these days. If we could "buy" other people�s contributions, I�m afraid it would become a routine and the site would become a Take Away. That�s not the spirit of it at all.
I share my materials here 1st because I do love making worksheets and I like the idea of other students around the world having the chance to use them, 2nd ,because I know that I can choose materials that are pretty much my style and use them with my students, saving me a lot of time, and 3rd because I can learn a lot from other contributors and become a better teacher, which will benefit my students.
So, let�s imagine you like my work and upload my worksheets again and again. You would donate money to the site, but what about me? Where is that worksheet I need (sometimes so desperately!!!)? Your money wouldn�t do me any good, would it?! So what would make me want to keep uploading my hard work? The other hard workers, that�s for sure, but I believe that in a month or 2 I would quit because it would make me feel uncomfortable knowing that some people would have the chance to "BUY" it without giving back anything to those who give their very best to keep this wonderful site running with their contributions. If I wanted to sell my worksheets, I would have contacted a Publisher.
Of course that we can always make some $$$$contributions, but one thing doesn�t exclude the other in my opinion.
A nice day to you all from the Azores! :))