Before refinishing bath fixtures, you need to go fixture by fixture and look at the costs involved in replacement versus refinishing.
A tub or shower can be expensive to replace and also leads to a cascade of other upgrade costs including wallboard, tiling and trim, and flooring adjustments. In that case, having a pro repair chips and cracks and apply a new finish can be a money-saving solution and stave off the need for a big-ticket purchase.
Sinks can also be refinished, but the cost of refinishing this bath fixture is so close to the price of a new unit that you're better off shopping for a replacement and a nice new faucet to go with it. As you consider refinishing bath fixtures, be advised that old, cracked, leaky toilets aren't worth the trouble of repair; instead, invest in one of the new WaterSense-labeled high-efficiency toilets, which can dramatically reduce your water bill during many years of service.