If you are talking about a hyd buffer they run about $80
I don't really notice recoil on a 5.56 so I couldn't tell you if any of the recoil reducing products work. A brake or proper front end control and stance will lessen muzzle jump in order to stay on target or control it for a quick follow up.
There is a Buffer Technologies recoil buffer that replaces the poly buffer end for $10.
Some say a light buffer reduces felt recoil, others say a heavy one does.
5.56, 6.8, 264LBC, SIX5.
The Nextgen of 308 rifles