Worked OK back in the 90s but back then prebuilts commanded a significant mark up over the sum of there parts. Its all stack em high sell em cheap these days which is hard to compete with when peeps are on a budget
seeing as i own a pc related tech company, i can tell you.... unless youve got 10k to drop on starting it........youll go no where. however, if you stay to doing local fixups and stuff youll build a reputation alittle faster, but then again you have to start somewhere.