Double post, but another pretty one...
http://cgi.ebay.com/Vintage-Alphia-X...item2a04b69354
It's the 20 pearl kind. I can't tell if it's Beta Kappa or Beta Chi. If it's Beta Kappa then it's a chapter founder's pin!
ETA: And this one just breaks my heart...read the description...the sellers sounds like a (former?) member....
http://cgi.ebay.com/Vintage-Alpha-Xi...item5ad6f9593d