Most of the valuable flat coinage is from Rama 4 or 5 reign (like in the 1800's). I have been to the eurseree auctions and the staff is quite friendly and will meet and talk with you. Vituun (as I recall) is the owner/operator, quite friendly, the auctions are also enjoyable and not a rip off. Most recent catalog is here: http://sale60.eurseree.com/