I'm not sure when you're going but it can get below freezing (20's, teens, even negatives a few days this year) with snow in some parts of the Tennessee mountains. I'm not sure what you have but you'll need stuff for layering. Check REI, Dicks, Sierra Trading Post, backcountry.com, etc online. They have sales off and on. If you're rather go into a store Dicks and REI have branches here and there and there are plenty local places. As for sales, winter gear is usually going on sale around now, especially in stores. Online you'll get a better selection of sizes and colors but in store you might get a better deal because they want to clear stock. Local outdoor stores, I find, sometimes have really good sales because they don't have the room to hold stock but the items are usually extremely limited. No matter what the quality stuff is pricy.