Just be sure to do your homework before making any deciscions about selling anything. Beckett sports cards makes a decent price guide that is inexpensive 7-8 bucks I think. Try not to value your collection as a 20k card lot , you will get more by selling the rookies and stars individually than any offer you would get bulk. The hobby has really suffered due to the poor economy and the new idea of premium luxury cards and packs. It has chased a lot of the younger generation away by making the most wanted packs 50-1500 a pack. Also if you have some of the greater stars and rookies in your collection CONDITION is huge in the hobby. A card worth $50 in near mint condition can be worth $4000 in gem mint 10. Baseball in those years suffered a lot since the 80-90's rookie class was the first ones out on the performance drugs bandwagon(bonds,mcgwire,clemens etc.) A lot of people heroes turned on them so they sold off their heroes card and the prices dropped. But theres still a few in demand, Have fun searching and watch those corners. PS. if they are 20,000 commons most people want about $200 to take them off your hands.