Worn out seat that has to go...

Any suggestions? I have an old KX 250 (88) that I have been riding quite a bit lately, and I can not put up with the seat any longer. AFter a few hours in the saddle my butt is so sore I want to take up a new hobby...na....I spend a lot of time on motorcycles mostly street riding, so it's not just conditioning. My riding buddies have all comented on the harsh seat after riding it. I just got a new seat cover, the new grippy type....nice.... My question is about seat foam. Could I go to an upholstery shop and buy a chunk of foam, and then cut and mold it to fit? I am trying to do this as cheap as possible...So I didn't want to to spring for the extra 50 bucks on a factory replacement foam piece. Thanks in advance.

J3R.... the seat is the same from a KX 500 from 87-00. That gives you good choices for color selections.... butt I'm more interested in the foam.