SFS tunes are very good the basic tune which leaves the gun very smooth to shoot with no twang and very consistant is £45, I believe Tony is now offering a Deluxe tune for £100 but I've no knowledge of this tune up so can't quote on what gets done and how better they shoot, the waiting time for Tony's tune up is about a week, V-mach on the other hand does a basic tune for £100 and a Laserglide tune for about £160 (I think) and a lot more work goes into them but the waiting time is pretty long (we're talking months), so it's your choice.
Pete