Saw Guitar Hero 3 instore at the Exeter HMV today with guitar reduced to £44.
The price label on it was hand written, so I suspect it is not national. Maybe the box was damaged - I couldnt tell. Neverhteless, may be worth a check if you are passing your local HMV anyway and are looking for some GH goodness!
Please don't shoot me down in flames if the deal becomes hot and then noone can find it locally!