Fun topic - a few things I picked up for a buck each at our town library yard sale last week:
McCoy Tyner - Reflections
Dr. John - Television
Putamayo's Cuban Lounge
Dan Hicks - Beatin' the Heat
You never know what you'll find at yard sales - 99% of it is Madonna and Kiss - but every once in a while...
I remember the good ol' days spending hours at Le Marche du Disc in Montreal where they had a ton of vintage r&b and blues for under $5 Canadian - things like Wynonie Harris, Little Willie John, Ruth Brown, Lee Andrews, etc.
Strangely, the best deals on vintage collections I've found have been overseas. In a little shopping mall in Portugal I found 'Cuban Legends' (2 cds), and a Big Joe Turner 4 cd collection, 4 euros each.