I've been using tablets religiously (i.e 10+ hours a day) for probably the last 7 years. I still use a shitty $60 bamboo. Ive had intuos and tried the cintiq. Unless youre doing something that REALLY needs some crazy pressure sensitivity you're fine with the bamboo for a long time.
I recommend used bamboos for anyone who wants to try out going tablet. $50-70 bucks is a lot safer bet than jumping in $300+ on a whim.