I don't want to sound "really, REALLY cheap" but like my Dutch ancestry, I'm thrifty.... So, There's a 3 gallon 100 PSI compressor at Harbor Freight that 4 years ago when I bought mine cost $39. Now, it's up to $49, but with a 25% off coupon, it's $37.50 (even cheaper than I paid 4 years ago).
While it's not as expensive and probably not as "reliable" as some of the higher priced compressors, it's been lugged around in the front compartment of my fifth wheels since new. It's inflated ski tubes, air mattresses, truck tires and trailer tires and still looks new. It draws 2.6 Amps, that's just a "tad" over 300 watts which means it can be plugged into a 400 watt inverter and run off the trailer battery or truck battery.
For every day use in a professional setting, I'd not recommend something like this, but for occasional use to air up a low tire (max PSI is 100) or for use in a camp setting, it sure has worked well for me and saved the rest of my "compressor budget" for "adult beverages".... It might be worth consideration for someone who only wants an inexpensive compressor to keep in the trailer.....
http://www.harborfreight.com/3-gallo...tm_source=1010