HI RKG, No one has mentioned the FREE BOX in Telluride. That would be the first place I'd look for warm clothes. It is in downtown Tride, and everything in it is FREE. Clothes mostly, but sometimes there are interesting items that make it into Town Park for the festival, and then end up back in the Free Box afterwards. It's about the only place I can afford to shop in Telluride.
As others have said on here, do take the time to read through the forums, and 99% of your questions will have already been asked by others and answered by many. (sometimes they stray off topic, but stick with it, you'll get there)! And you are smart to even start thinking about 2013; it will be the 40th Telluride Bluegrass Festival, so LOOK OUT! Try to plan some extra time before and after the festival so you can acclimate to our beautiful state, and take in so much of what Colorado has to offer: Hiking, biking, rafting, climbing, jeeping, parasailing, paddleboarding, skiing (snow and water), rockhounding, gold panning, ancient cliff dwellings and Indian ruins, and the ever-popular DRINKING! Lots of breweries beckon, and some wineries too.
Bet you wish you were coming this year, huh?