Gamestation is selling "UFO Trilogy" for the PC for £9.99 (inc Del.)
You can get 5% Cashback through TopCashBack on top of this making it just £9.49 (Quidco don't seem to offer cashback for software)
Next best brice is £14.49 from PowerPlayDirect.
Great price for 3 critically acclaimed PC games: "UFO: Aftermath", "UFO: Aftershock" & "UFO: Afterlight".
It's also available as part of their 2 PC Games for £15 offer, but you need to check the prices carefully as many of the games in this offer are cheaper elsewhere.