Ray, Yes the inverter is your best best. Economical and reliable. You will need 240 volt single phase. They do make 120 volt inverters with 3 phase output, but not for motors over 1hp. Check (www.KB_Controls.com) for 120 volt.
You will most likely not to have to derate. Most inverter manufacturer's require no derate in the smaller HP ranges.
You also eliminate stop/start and overload relay.
Your best price may be at http://www.automationdirect.com.
If your situation is just to run the motor at full speed then you will only have to program for the quick start.
Basic installation and neccessary program settings.
Make sure you connect it for single phase. Some require a jumper for the spare terminal. Read the manual!