A fellow of me find these on ebay..
http://cgi.ebay.de/Wein-PX625-Battery-1-35Vo...&hash=item3ef9fc80e2
It´s not up for sale in this link anymore, try a search on ebay.
Found it here instead
http://cgi.ebay.de/Wein-PX625-Battery-1-35Volt-Yashica-Mat-124-Mat-124G-/270482047202?cmd=ViewItem&pt=Film_Cameras&hash=item3ef9fc80e2#ht_5311wt_1139
Regards
Tommy Hjorth