Popolocrois, PSP - £7.93 delivered
PaRappa the Rapper, PSP - £2.99 delivered
Farcry, PC - £1.99 delivered
For those of us who can't run Crysis, this is the next best thing. Looks pretty great on a modern machine, with all the woofers and tweeters turned to 11.
Timeshift, PC - £1.99 delivered
Based on the demo, it's pretty bad, but £1.99 for a modern popcorn FPS with an interesting gimmick is probably a good price.