Make them if your cheap like me. Went to Harbor freight the other day to buy some gloves for work and they had so aluminum thingys that bolt to 2x10's. They seem to work pretty well. A little bit heavier than the aluminum ramps but it only cost about 30 bucks to make. I'll take some pics if you want.
You can check here with this guy, I know he sells them.
http://www.golfcartgiant.com/ramps2.html