As far As I know, there are two persons in this webboard who does business on selling Summoner card, the first one is Mr. Champ and the second is Mr. Sorrayuth.
Mr. Champ has his own card store on Maboonkrong Center called "Heaven Light", and also has his own website for selling Summoner cards. Mr. Sorrayuth also sells Summoner cards, too.
But, as I know, the two of them sell cards to their clients in Thailand by using post mail to deliver the cards. I've never seen any client from other country before ... (may be they do have some, but I don't know) But, if they do, of course, the price has to be more expensive than usual.
Anyway, I suggested that you should contact them directly. Mr. Champ's website is
http://www.hlunderground.com/forum. And for Mr. Sorrayuth, you might contact him through I.M. system of this webboard (I'm sure you know how to use it.)
Hope this could help.
Good Luck ...