While the idea behind your site is great... Basically all it's full of is scammers posting open source scripts with modifications.
Unless you're auditing and doing quality control on the content of your site you are basically supporting scammers
I do quality control. While anyone is free to list on my site, if I see something of poor quality or something that is pulled from github, I remove it. I selectively pick sellers I know are legit, and allow them to list for free. I also check demos for functionality. I would be willing to do code audits if a seller agreed on it.