I would advise a Singer 95 (very old, but simple and strong as hell) or a Singer 491 (1970's-1980's). You might find a 95 for under $100. The 491 will go between $250-$350 if in decent condition. Given the choice I would go for a good 491. Anything newer (591) is too fast and the stitch is not as good. Yes, we figure at 14 buttons per shirt. Two per collar. Five for sleeves/cuffs(which averages out single and double button cuffs). Seven for front. EDIT: Pfaff is also an excellent machine. They aren't as prevalent at the used machine dealers, however. No Juki (except sergers), No Union Special unless you want double-needle chainstitch, No Consew, No Reece, NO NO NO Brother, No home machines.