I currently use a Weibad Cheek rest pack on two or my rifles. They're very comfortable and easy to adjust. I also have a few neoprene pads (almost like mouse pads) that have adhesive on one side. Just cut it to fit and stick it on.
You can get rolls of 1/8in thick neoprene foam with an adhesive backing online for about $15-20. That works perfectly, since you can put a large piece on top of your cheek rest, then just trim it to fit the cheek rest exactly.