Amazon have been discounting the latest Mac titles for a while (So have Play incidentally) and though some of the prices have gone back up (EA Sports titles) some are still bargains - particularly compared to the Apple Store and other retailers - so I just thought for the sake of other Mac users who hadn't come across it I'd flag it up...
X-Plane 9 (2008 £49.95) £29.98
Neverwinter Nights 2 (2008 £39.95) £19.98
Enemy Territory: Quake Wars (2008 £39.99) £19.48
There's many more with £5 and £10 off RRP (including Unreal Tournament 3) but it is worth keeping an eye on them and of course there are loads of 2nd hand titles for sale on their. Hope this helps!