I'll add it to my search list; it will take a while though. The last one I saw at a PCB shop in Akihabara was well over a year ago.
My two cents (if it matters)
I've put time into original boards at game centers like Hey! and Mikado. My PGM cart at home feels exactly the same. If your main goal is truly to work on a high score, I really recommend just getting a cheap PGM motherboard along with a cart. It'll cost you less than 180,000 KRW (about $150 USD) to acquire both after shipping to South Korea.
You can always buy the original board later (for collection purposes). By the time an original appears for sale, PGM motherboards and bootleg carts will have likely increased in value a little bit so you can easily get your $150 back. You might even profit.
Why wait up to one year to acquire an original board if you can play the game on the same hardware right now?