I've highlighted the good deals for good games. 

After Burner: Black Falcon - £19.99 (Play) RRP £29.99
Crush - £24.99 (Play) RRP £29.99
Diner Dash - £17.99 (Play) RRP £29.99
Driver 76 - £24.99 (Play) RRP £29.99
Heatseeker - £24.99 (Play) RRP £29.99
Legend of the Dragon - £14.99 (Play) £19.99
Metal Gear Solid Portable Ops - £21.49 (PowerPlayDirect) RRP £29.99
Pirates of the Caribbean: At World's End - £24.00 (Virgin) RRP £29.99
Ratchet & Clank: Size Matters - £24.99 (ChoicesUK) RRP £34.99
SOCOM: Fireteam Bravo 2 - £17.97 (Asda) RRP £29.99
Valkyrie Profile Lenneth - £17.89 (Sendit) RRP £29.99
Virtua Tennis 3 - £17.99 (ChoicesUK) RRP £29.99

£21.49 delivered to your house for MGS Portable Ops is a great deal, as is Valkyrie Profile Lenneth a whopping £12 off RRP, makes it, alongside Virtua Tennis, SOCOM: Fireteam Bravo 2 and After Burner virtual budget titles.

So this was a post on another forum, but I think the list on it has a lot of the really good stuff on the PSP: http://www.neogaf.com/forum/showthread.php?t=150539 I really think the PSP is underapreciated, I don't care if it doesn't sell as much as the DS, I still play it a lot more and like the lineup of games better... Check those games out davygee, great stuff on there; DJ Max Portable is great, gotta import it though, hooray for region free PSP :D

I saw Killzone Liberation and Locoroco for £15 each delievered from amazon