ChoicesUK are selling "Ridge Racer" for the Sony PSP for £6.99 (inc Del.)
You can get cashback through the usual sites (e.g. 5% Quidco, making it just £6.64)
The next best price seems to be £10.99 from SoftUK.
Featuring the best loved race courses from arcade classic Rave Racer and the entire Ridge Racer series, 24 circuits of breakneck speed and exhilaration stand between you and racing glory. Beat the clock in Time Attack Mode or test your racing skills against up to 8 players in WiFi compatible Wireless Battle Mode.
- Reworked and enhanced car design, complete with trademark Ridge Racer series drift handling
- Drive in style and rise through the ranks to unlock hidden bonuses in World Tour Mode
- Featuring 24 breathtaking courses, the most in any Ridge Racer game