The Atari 7800 did many things right: it was compatible with the 2600, could produce some really good 8-bit graphics, came with a modest price tag and radically improved the 5200's atrocious controllers. It did thus sell decently too and even has a lively homebrew community to this very day.
Retro gamers and collectors interested in getting into the 7800 should look no further than this amazing Atari 7800 & games auction. It's for the complete, boxed, PAL version of the console (with cables, manuals, 2 controllers etc), 15 boxed 7800 games and 11 boxed 2600 games. Seller ships only within the UK.