Since these things are getting tougher to find and, combined with a giant squid are an excellent additional audio source, I figured it would be ok to post this link that I found on Ebay. I have two and don't leave home without them...the bid is at .99 right now, I"m sure it will go up before it closes tonight.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290017010532&ssPageName=ADME:B:FSEL:US:1