Having purchased a couple of Guinea Pigs the other week, I've realised that they're a lot like videogames: they're great fun to play with, both alone and with friends, and whilst they have a high intial startup cost, the benefits you'll receive from them are well worth the asking price. They also cost around the same, but, whereas my Guineas will bring happiness to my home for the next 4-8 years (here's hoping much longer), games don't quite seem to last that long.
Xbox 360