REI also sells wax. Grab some, a cheap iron, check out some of the how to videos, and you can easily do it on your own as well. This will help you keep your skis fast all year! I like to throw a coat of wax on at the end of the season and let that sit until the start of next season before scraping to keep the skis protected. For any deep gouges in the p-tex, core shots, or edge damage though, I would take that into the shop unless you really want to learn some extra repair skills (which aren't really hard, but involve more materials and time).
like @Diesseldorf said, I sooooo recommend you learn to wax your own skis! I find it really satisfying to repair scratches w a little ptex, then wax-on, using my trusty 'garage' iron, (doesn't everyone have a dedicated iron laying around in the garage, lol?) Then wax-off!
recommend getting a book or watch some vids so you don't damage. you do need some stuff..clamps, old iron, a variety of scraper tools, something to clean and sharpen the edges, some candles to light the ptex, then a good rasp-bastard file to grind it carefully down, then the waxing can begin.
a little shop vac works wonders to get all the scrapped wax off the floor. enjoy!
here's an awful vid I filmed, just for fun prior to leaving for Colorado and a ski week at keystone