You can find alot of portable(fold up)shooting bench's at most sporting good's site's? I'm lucky in that I have a concrete picnic table in the side yard that I bench off of but it only give's me 20yd's. When I need more distance I use a camera tripod with a bag on top or a metal fold up saw horse.
Oops, sorry -- I misread your post. I thought you wanted a portable. Here is my backyard bench.