Dent removal can be very costly. An affordable do-it-yourself dent removal kit such as Ding King and DentOut is a great alternative to the cost of a body shop or a somewhat cheaper "paintless dent removal" specialist. These dent removal kits cost about $20 to $30 and can be purchased online or through infomercials. The dent removal works by hot-gluing a suction cup onto the dent and pulling the dent out using a special device provided by the kit. The results are not perfect, but are generally satisfactory. The kits are most effective on dents about 4 inches across and only become less effective on dents less than 1 inch in diameter.
As a caveat, the more experience you have with the dent removal kit, the better the results. Common pitfalls to avoid when just starting out are careless handling of hot glue and pulling the metal out too far.