If you're looking for a case with an integrated keyboard, Kensington offers one of the better values with its Kensington KeyFolio Pro Performance Case. The version with the "fixed" keyboard is going for $49.99 on Amazon (it lists for $99.99) and the model with the removable keyboard is selling for $62.99.
Like a lot of these keyboard cases, this one's on the bulkier side, but it does have a couple of nice features. First, you get hard keys on the keyboard (some keyboards have soft rubberized keys) that are more tactile. Secondly, the swiveling hinge integrated into the case allows you to prop up your iPad in a horizontal or vertical position.