As with any skilled trade, getting a piece professional upholstered can get expensive quickly. One way to cut down on the price is to buy your own fabric separately, from a discount supplier or other such vendor. We recommend using a heavier-duty fabric, such as canvas, to prevent early signs of wear. There are lots of sites available for calculating the amount of fabric needed - we like Domino's, as well as this site which offers a little bit more technical information for more complicated projects.
If you've inherited a cheap piece or thrifted something inexpensive and don't want to put a lot of money into it, you might consider trying to reupholster it on your own. Make sure to check out some guides or books to help walk you through the process.
Best of luck, and we'd love to see any finished products out there!