Check the motor specs and pump RPM. 5HP is pretty meaningless when it comes to compressors. Compare CFM @ some PSI. The 5HP Baldor motor on mine is rated at 23A @ 230V.
You might troll CL for a while to see if you can't find a quality used compressor for less money. For example:
http://dallas.craigslist.org/ftw/tls/2130903454.html
Its kind of a funny example since its duplex but I'd guess its an expensive compressor if bought new.