The guy in Korea who is making the mockingboards, now has one up for auction on eBay. The boards are new, but according to the description the chips are used.
http://cgi.ebay.com/mockingboard-for-apple-ii-ii-iie-sound-card_W0QQitemZ180300483228QQcmdZViewItem?hash=item180300483228&_trkparms=39%3A1%7C66%3A2%7C65%3A10%7C240%3A1318&_trksid=p3286.c0.m14