When we moved in, our old clawfoot bathtub was in bad shape. It was stained and the finish had worn away. Our landlord wasn't going to replace it, but after some coercing, we convinced him to reglaze it for us. For less than the cost of a new tub and installation, porcelain and cast-iron tubs can be reglazed and the finish restored.
We've lived with our reglazed tub for about 5 years now, and it's showing some wear. It has chipped in a couple of places, but it's still in great shape compared to the way it looked when we moved in. Eventually, it will probably have to be reglazed again or replaced, but we're relatively happy with the results since our options were to live with the tub we had, or go the reglazing route.
Since our landlord negotiated the work, we're not sure about pricing, although we've heard a few hundred dollars is standard. This issue has come up a few times on Apartment Therapy and you can follow these links for a little more information:
Image: Reglazed Bathtub from Salvage One, $1,350