I guess we need to know what you mean by "cheap"... Are you looking for a shoddy piece of crap or something usable that doesn't cost much? Personally I'd look at a Craftsman if you're looking for the usable inexpensive kind, they run good sales on powertools all the time. Be careful of the off brands, I can't think of the name Sears has that K Mart sells (maybe Companion?), but I bought a miter saw for some junk work I didn't want to use my good one for. It was outright dangerous.
I have a Craftsman benchtop scroll saw I take to jobsites to back cut molding miters. It takes a lot of abuse and is a fairly solid piece of equipment. I think I paid $60 for it a couple years ago. I personally don't like the quality, sturdiness, or safety of the HK, Harbor Frieght, etc... off brands.
Pawn shops are great for this sort of thing as well. Two of the local shops always have things priced like they have a new item and usually they'll deal a little. The third local has things marked at least close to reasonable and sometimes will make a great deal. Shop around even at the pawn shops.
Good luck and let us know what you're really looking for....
Tim