It seems odd to think of repair kits for early Macs, considering that 5 years ago you couldn't give one away, and Goodwill had stacks of them for $5. At the time I figured there were enough of them that like Model T Fords, there would be plenty to go around for the next 50 years and they would never become rare or expensive. The difference is we didn't used to recycle stuff, and a worthless Model T just sat out behind the barn or quietly rusted in a junkyard. Now we actively destroy obsolete stuff, so things really DO become "rare" pretty quickly. Also modern electronics have "time bombs" which will certainly disable them like electrolytics, and custom chips which go out of production with the particular model.