Ebay can be hit and miss for quality of photos. I have noticed that a lot of those photos can also be accessed on the library of Congress website (but you might have to do some digging) and if you have a good printer and photo shop you can print out some nice results.
Also, George Brace's daughter runs a website where they print out his photos from the original negs. They have a online catalog and the quality is outstanding. Here's the link.
http://georgebracephoto.com/index.html
Hope that helps