I won't disagree with Ed but if money is an issue there are some surprisingly good motors for not a lot of money.
By the way, most grinders I've seen and all I've used take 1 phase motors. If you shop doesn't have three phase power you won't want to go there.
My favorite comes from Grizzly, a 1 hp TEFC I use on a Rock saw. They are $190, less on sale. Mine has been working for years with no problems at all. (
http://www.grizzly.com/products/Moto...ce=grizzly.com
An equivalent (spec wise) Lesson will cost about $100 more, a Baldor about $160 more. They might be better motors but........
I've even had great luck with the $159 Harbor 1hp Harbor Freight Farm Duty TEFC motor. Been working on a home built grinder for over four years - used several times a week, never a problem.
I have a friend that purchased a Grizzly Knife Belt Sander/Buffer(about $550) and LOVES it.
http://www.grizzly.com/products/Knif...ce=grizzly.com Motor: 1 HP, 110V, single-phase, 14A
Motor speed: 1725 RPM