I have a collection of phonocards, that is postcards, with music records on them. How can I get them valued?

The pictures all depict Hungarian scenes and the music is Hungarian. They are made by Qualiton Studio by Budapest Hanglemezgyar. They are at least between 30-40 years old. They all play music well on a record player. I have done an internet search and can only find very limited items. Can some one tell me where I can get these valued please

This phono card on Ebay is up for bid. Maybe you could email the seller and he could give you some idea of past sales on these items.

http://cgi.ebay.com/PETER-T-WARD-WHITE-SOX-PHONO-RECORD-CARDS-1962-MINT_W0QQitemZ120129390893QQihZ002QQcategoryZ37592QQssPageNameZWDVWQQrdZ1QQcmdZViewItem