My local Virgin Megastore had 21 copies of Pilot Academy for the PSP priced at £5, until I nabbed them all, that is! Pilot Academy is very similar to Pilotwings, is rated 6/10 at http://www.pocketgamer.co.uk,
and is a flight sim with loads of planes and levels.
However, the best thing about it is that it is worth £12 trade at the moment.
The Virgin website has the game listed at £35, but these went through the till at £5 each, so if your local Virgin has them in stock, this is likely to be the price you'll pay. I also got 10% student discount on my games, and was then given a brand new student card too, as they've just changed them. I've not been a student for years, but I have found that if you ask for a student card, they'll usually just ask what Uni you attend (you might need to say you've left your Uni ID card at home). If it doesn't work the first time, try upstairs! It's worth it for the 10% discount without having to get the credit card.
A picture of my purchases (i'd removed the prices from half of the boxes ready to trade them in) in another one of my recent finds- although they only had one of these chairs in stock so it wasn't worth posting here!)
If the £12 trade price stays at that level, and you buy 20 copies for £4.50 each (with student discount), you could make £162 trade profit fairly easy, almost enough for a Wii...