2600 Connection . Newsletter for collectors. There is also a list of label variations kept here. Jason Cody's Atari Jaguar Page . Includes quiz to test your atari knowledge.
Extensive catalogs run out of a store in California.
Very fast service and high turnover rate. Their specialty is filling your want lists. Send one over to them and they'll do their best to fill it at no extra charge. Limited selection, but look here first if you need something, especially for the 7800. Many other systems too, though.