i have a 4" makita and (for all the canadians on here) a mastercraft 4.5". both have served me well. i just leave the wire wheel in the makita and switch zip disks and grinding wheels on the mastercrap.
if the 3/8 one is the only one you can find. just get a 3/8" to 1/2" adapter to add to it.
go to any store that sells quality ratchet sets, maybe even canadian tire! the best store on earth(them americans don't know what there missing) :cheers: