Sometimes if you go to Albertsons, Safeway, Brookshires, etc. they have the machines and various "soaps" and it is almost easier to do it yourself. You have a time limit but you also have control over the situation (if there is one particular area, you can concentrate on that, etc.).

Stanley Steemer is probably your best bet if you're worried about chemicals and residues.

Just a tip, don't forget to check your phone book for any applicable coupons no matter which way you go!