binpress does this already: http://www.binpress.com/. I've purchased iOS components from there in the past. Not sure how active/popular it is currently. As others have said, there's also flippa, hotscripts, etc.

I like the idea and I'd look into selling some code (I have a collection of Sinatra apps I re-use for all sorts of things from APIs to payments). The issue really comes down to support, customization, and deployment. I don't mind writing some documentation once, but I don't want to spend 4 hours supporting something I sold for $299.

Ignore the people that say there's no market. One way I think you make this stand out is with a "verified" badge of sorts. For any project, ensure that it has one or more of the following:

- Dockerfile that works

- Deploys to Heroku with min. effort

- Has a test suite that passes

- Has a working demo

- Includes a minimum amount of documentation/setup videos

That's my 2¢