Definitely look used, OLD craftsman, baldor, walker turner, OLD delta. A 6" will do almost everything in the home shop. I have two, one with grinding wheels setup for sharpening lathe tools and drill bits other side has a dedicated wheel for sharpening TIG tungsten. The other has two wires wheels on it for cleaning.
One is a c list old delta that I picked up for $20. Needed bearings, but now runs smooth as silk. Other is a late 1990's cman, that I bought new on clearance for $50. Came with a stand that I sold for $20. Nice grinder, not sure what they go for new these days from sears though.