We are looking at stone facing our new garage. Current estimate shows its cheaper to get newly cut stone, than pay a Mason to cut/clean/sand blast reclaimed stone. Obviously material and labour costs will differ between locations.
I would consider cutting some kind of deal with the guys taking down the building, like you only charge them $20/ton to dispose of their stone on your site.
4xdog - the garage you post in your first group of pictures is block construction with stone cladding, compare the interior picture with your friends barn.
We have a lot of stone built stuff around here, none of it built to any kind of code, but it will be here long after we are gone.