there are some knockoffs on ebay for 20-30 bucks.
I used one on a build a while back as i thought it looked cool, and it worked better than a bare muzzle, but really the .223 generates so little recoil impulse that mostly its muzzle rise that i notice, even when shooting my 6.5 fast.
the boring on the cheap one is probably larger than the VooDoo, which reduces the effectiveness of the air strippers, so you may or maynot notice a difference between the "real" one and the knock off.
Honestly if you LIKE that one, save up for another month, your only gonna save 50 bucks at most buying the cheap one.
In terms of recoil reduction and not disturbing the sight picture, ive found the peperpot break that came on my 6.5G to be excellent. Before i had the barrel turned down the gun would shake under recoil but not really move. Now the bolt carrier cycling will move the gun a bit, but the shot is still pretty steady.