Shameless plug:
favorite_things
I sell mostly postwar, food issue, test issue and unusual stuff like venezuelans- a mixed bag - I've been selling (and buying) on ebay since 1998 - 99.2% positive feedback (1 negative in 20 years - can't please everyone I guess). I list very intermittently - so you may want to save me as a seller and get emails when I list. Some of the items are pretty rare and get snapped up quick. I am more negotiable off ebay with the net 54 community.
Sellers I've had a good experience buying from:
Lukesvintagecards (mostly prewar) - just started dealing - had a great experience - hope to buy from again.
PWCC - so most of the time I am unwilling to be shilled higher. That said, there is no question they have the goods. I always snipe so I never pay more than I want for a card (I probably win maybe 1 in 20 snipes - a couple times actually well below my bid - too frequently I am the underbidder
)
4_sharp_corners - usually at or above the high side of the market, but once again - they have the goods.
Tampabaycards - for Venezuelans