I've been looking out for a good deal on folding Gatorskin 700c x 25s for a while now, and finally one has come about!
RIbblecycles currently has 20% off all tyres when using code 'TYRES20', which includes twinpacks. This makes the £44.99 twinpack a brilliant £35.99 - thats £18 a tyre! With free delivery.
Plus these are the slightly more expensive folding ones instead of the wired.
Great price if you are after some. I can see from searching that the last best deal was at Halfords 4 months ago for £18.39. Code expires in 3 days.