There's really only one card shop left here in town (a travesty, for sure) and that's Sports Collectibles of Houston. You'll have to hunt through boxes organized by set for the most part, so a want list will go a long way for you. There are a few tubs of cards that have been grouped by decade (50s-60s, 70s, etc) but for the most part he has a lot of stuff organized in boxes on the wall.
The stuff in the tubs is slightly lower grade usually, and already priced. The stuff from the boxes he'll look up and price at about half of book. If you start making a pretty big stack he'll probably give you a discount.