Once you're in town, you'll see all the shops have touristy TShirts, stickers and similar stuff. Most will be related to hiking, biking and off-road enthusiasts.
For vendor specific stuff, don't miss the Vendor Showcase. Im not sure when it is, but I'm sure anyone atending will know. Last year it was the Thursday of EJS. Don't go too late though, many vendors outside were closing up shop about 4 when the wind starting kicking up.
Last year I got a couple growlers of micro-brew at the Moab Brewery to take home. Great stuff!