Fancy,
http://www.chiefaircraft.com/radio-c...b-100stof.html
Simple
http://www.pspmfg.com/RCStandOffsMotorSpacers.html
Or if you're cheap like me you go down to the hardware store and buy a piece of aluminum rod and cut and drill them yourself
here's the last set I made, 1-3/8" w/ #10 bolts
good luck