Just ran across this while at HF the other day picking up an air hose:
7" Variable SPeed Polisher / Sander - $35
It's a Harbor Freight piece of power equipment so in no way would I expect it to last. However, for $35 it is 1/3 the cost of the Porter Cable unit and if it's for home use it probably won't be used all that much, maybe once a month? At that usage rate it'll probably last years. It has no random orbital feature like the Porter Cable unit but it does have a nice 300-3000 rpm speed range.
Just a thought if anyone is interested.