Playasia now has stock of the KOFXIII Edition of the Fanta Stick PX, according to the product description it has compatibility with both Xbox360, PS3, and also PC.
At £64 it is not a bad price for a stick that is dual supported right out of the box, although shipping seems to be quite high at £48 for Fed Ex. (No ordinary shipping options appear to be available on this item.)
If I wasn't heading out to Japan next month I'd probably consider importing it, hopefully I'll be able to find it at some point whilst I am there.
Also confirmed by Playasia is that the US version of KOFXIII for 360 is region free.
Apologies for the lack of blog updates lately, as I mentioned I am currently preparing to spend a year in Japan so I have had quite a lot of things to sort out and pack away. =_=
[Edit]: As pointed out to me by Gunsmith, you can find more details about this stick on Gammac's website, which shows all the features of this stick as well as images of it's internal parts.