do not see how to change drive belts
how to replace drive belts on 1993 3000gt on 1993 Mitsubishi 3000GT
You can get an estimate here www.repairpal.com/estimator and find a shop here www.repairpal.com/directory
It is not to big a job to replace the belts. Look at You tube there are several videos similar to your car. I think I saw one on a Honda Accord same style of adjustment as your car. Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info .There is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You get a one year subscription to year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual. http://bit.ly/alldata_repair_manuals or try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription.