In the 1975 set, the expensive ones are: George Brett rookie card is $100 in mint condition, Nolan Ryan and Hank Aaron $50 each in mint condition, Gary Carter and Jim Rice $30 each in mint condition. Condition is everything. If the cards are in good condition, consider getting the ones mentioned above graded. PSA or CGC grade cards and you can mail them in. Grading ups the value if they are in good condition. At that point, can sell on Ebay. Selling at card shops generally don't sell at top dollar This advice is coming from my husband. He has been collecting baseball cards for over 40 years.