If you look closely you will find that most homebrew games are available for purchase or download.
Check packrat videogames, kristof tuts homepage (Vector Pilot), madtronix (for vectorzoa games), Luchs soft, binary Star soft (bins and upcoming releases), Revival studios and fury unlimited (free bins) for a start. You can find some of furys discontinued games at gooddeal games. You often see homebrew games sell on eBay for insane prices which are available from the developer for cheap. There is tons of stuff to get and unavailability is more the exception than the rule if you look closely and have patience with the publishers.