The standard Wacom tablets are expensive because they're classed as "professional" tools. Don't be put off by the relative inexpensiveness of the Bamboo, though - it's Wacom's attempt to corner the amateur/semi-professional end of the graphics tablet market. Bamboos have received some good reviews:
Wacom Bamboo Graphics Tablet - TrustedReviews
Wacom Bamboo - Review - Tech.co.uk
Wacom Bamboo Review - PhotographyBLOG
If you simply
must have a Wacom (and still have money left for food), then I think the Bamboo is definitely worth thinking about. On the other hand, Wacom aren't the only manufacturers of tablets. As I mentioned above, I use a Trust TB-2100. It's about half the price of a Bamboo and probably lacks some of its fancy features but it does everything I need it to.