Hi Jim - Hope you are doing well. For what you are using it for the capacitor probably is a Start/Run type. Not sure what kind of circuit you have there on the compressor but for bigger motors there is typically a start capacitor that is switched on during a start up and it is switched out of the circuit through a relay or contactor and a run capacitor kind of takes over while the motor is running. I dont know what you were going to pay locally but chances are the one you found would work. If not, you take a look at Newark Electronics -- We deal with them all the time. I didnt read up on the specs, but this one might work also (Looks like its about $6.50 ....
http://www.newark.com/cornell-dubili...tor/dp/72K6669
Let me know how you get on with it
73
Mark