Thrift stores and used sports goods stores... Prices ranging from 5 to 20.
Left to right:
Dunlop Max 200G J.Mac sig, hardly a scratch to it;
Prince Spectrum Comp 90 (came with original leadther, I replaced it with lightweight overgrips only);
POG 90 4-stripe (they were twins, one given away to my hitting partner) came with original suede bag;
Prince Boron 110, close to mint condition;
Queen Elizabeth's personal racquet (susspected, bears insignia)