Mountaineer AWD transfer case explosion!

Not too much luck this Christmas with my 97 Mountaineer with an V8 and AWD.Upon slowing down from highway speed to about 35 mph, I heard a loud thunk and a explosion underneath my Mountaineer. It's was my AWD transfer case disengrating and grinding like crazy. Due to the holiday's the Mountaineer is sitting at home waiting in line to get a transfer case. I could really use some advice on what to expect from a mechanic and how much this adventure is going to set me back. Can a used transfer case from a junk yard be a reasonable option or would I be asking for trouble? Maybe Ebay or some internet shop with a rebuilt? Sorry but I'm confused and need some help. Thanks for any advice.