To be blunt, 50% commission is ludicrous. There is so much potential in this site but it will never grow with such high rates. Consider that Bandcamp's rates are 15%, droppjng to 10% with high sales, and that is what you are competing with. The combination of music, libraries, indie dev software and a forum/community is a great concept but as membership figures and participation here demonstrate, there's something holding it back. That is more than certainly the high commission rate. How successful would this site be if pro's saw it as a viable outlet, for both music and software? I don't just say this as some random young kid passing by. I've been in the music business for the best part of forty years now so I don't speak from a position of ignorance...
Consider this:
50% of 100 sales at 1 unit is 50 units.
15% of 1000 sales at 1 unit is 150 units
10% of 5000 sales at 1 unit is 500 units