A collection of super-rare signed contracts for some of baseball's biggest names -- including Mickey Mantle and Hank Aaron -- is up for sale ... and they're all expected to go for insane prices!!
RR Auction tells TMZ Sports ... Mantle's 1953 deal with the New York Yankees (with a $17,500 salary) headlines the lot ... and the historic pieces of paper are estimated to land a $50k price tag.
Mantle's contract is signed "Mickey C. Mantle" ... in which the legend agrees to provide "skilled services as a baseball player during the year 1953," according to the paperwork.