Well I forgot to update this post with what we found. At the first thrift shop we got variuos fleece and nylon/polyester tops and bottoms for the kids. I got myself a polyester sweater and a silk blend shirt. Nothing special, but they fit well and were comfortable. At the next place I got a fleece full zip shirt and got my son a polypro top. I used polypro alot in the Army and it's great stuff. I have literally fell into icy water and still stayed reasonably warm with polypro bottoms under my BDU pants. Also I did find a Patagonia fleece top but I think it was a womens top, it had lavender accents and there was no chance my son would wear it. I look forward to going back by and seeing what else shows up!