You usually do get what you pay for.
But if price is an issue, look at the servers and see what kind of setup they are. Do they have redundant power supplies? Is it a RAID setup in case a disk fails? etc
Rackmount or tower, they both do the same thing, and there's no added reliability in either design. However, rackmounts were created for a reason - organization and ease of use for the colo itself. Rackmount equipment is more expensive, but any colo or data center or business with many machines, wires, etc will spring for the more expensive hardware because it makes their job easier and more efficient. A facility that still uses towers is really just amateur and is getting by with cheap hardware.
That's the part I'd be worried about.