I got mine from a former member here named offsidewing. Necromancer bought the rest of the set. So basically, neither of us can be of any help to you since:
a) offsidewing is no longer a member here.
b) Unless offsidewing is the business of manufacturing these, I highly doubt he has any more anyway.
That said, you can always ask around here. Toshi @ Dream Stars Japan on eBay always has some of the wireless controllers in stock. Last I checked he had a couple brand new ones, even. But you'd still need to find a receiver to be able to use them. Far be it for me to recommend eBay, but Toshi is one of the few "store" sellers there that I will buy from. Unfortunately, he's in Japan so it's usually a good idea to buy a few items in bulk from him to make the shipping cost worth it for you. He always has great deals on loose HuCards.