GinSan repairs the MultiTron acceptors, but I wouldn't bother. They're not reliable.
I've never tried a MicroCoin, but everyone I know who uses them says they're great. I've installed and programmed some, and that's really easy.
Slugbuster is probably the least expensive and they're mostly reliable, but IMO they jam too easily. Slugbuster II's will take a $1
coin and only give a quarter credit, so if you don't want your customers getting ripped off and mad you'd be better off with the III.
I like the IDX MA800. Rarely have jams, very few problems with them, and when they do need a repair it's fast and cheap.