The cheaper units are basically rack mount power bars like you said.
For Furman, this is the cheapest I would go: FURMAN PL 8 II PL-8 SERIES MOUNT POWER CONDITIONER - eBay (item 200438496153 end time Apr-12-10 09:55:01 PDT)
And this isn't because I'm some kind of expert, but just because that seems to be the general consensus from what I've heard. I have the ART SP4x4 Pro. It has pull out lights and a goose neck lamp in the back which I taped to the top of my rack case. It's pretty nifty, and was $135 CAD new, so it would probably be a lot cheaper in the US. I don't know if the power filtering is as good as the Furmans, but my wiring is pretty decent and I've never had any noise problems. When I looked at the specs, I didn't much understand them when I was comparing the filtering with the Furman PL2, but from what I could tell it looked pretty similar. I was mostly concerned with power distribution though, and surge protection.