I got a cheap-o digital one for free with an order from VXB bearings (sign up for their newsletter, they give them out all the time). It works fine for the level of accuracy I need (not a whole lot) and the amount I use it (also not a whole lot). If I did a lot of custom fabrication or had a job where I needed to use the caliper on a daily basis I'd spring for a decent one, but if your use habits are anything like mine I think the cheap ones are fine.

The cheap ones are rated to have the same accuracy and resolution as the pricier Sear's one Duster_360 posted (not saying they actually do as good, but they claim to), and I'm not convinced the Sear's one would survive a drop any better than the cheap ones.