Your location will make a difference on the price. Assuming you remove the heads (not doing the 1 at a time), I received quotes from $3500 to $4500 which included decking the heads and magnaflux. If you do have them done I would suggest upgrading the valvetrain (springs and push rods) and replacing the rockers and lifters (OEM). This is also a good time to do a 6.0 exhaust manny and upgraded up pipes. IMO, as long as you can have your truck down for a little while, if you aren't puking or don't plan to do other upgrades while in there, I would wait until you have an issue. There is a pretty good chance your HG will eventually fail, your up pipes will crack, or your HPFP will start to get weak and that's when I would do them.