If you just need the rear adjuster I can whip up a few on the lathe for a few bucks each. I had to make one for a Sniper 1 I restored. They'll use Sheridan springs though.
American Paintball has the springs for $2 each: http://www.rcpaintball.biz/e-commerc...-catalog6.html
Palmer's also has them for $4 each.
Here's a pic of the one I made:
PM me if you're interested.