I don't really see £50 as too much for a game because that's what all N64 games were. I tend to buy all my games from stores, such as Game, and it's very rare for a game to be priced at £50. However, if I do see a game at that pricepoit I'll probably go elsewhere since I know I can get it cheaper (where I live there are 2 GAMEs, a gamestation, a HMV and a large Tescos all within a 500ft radius).
Anyway, I'm waiting for a price war between the supermarkets tomorrow where I should be able to pick Black Ops dirt cheap.