Well there is a BIG problem with Otaku Filcos. They are almost impossible to get.
Are they? Keyboardco will sell you one any time you ask, I believe. I guess you meant they are almost impossible to get from US dealers.
One of the keyboardco guys told me they actually make blank keyboards by switching the keycaps themselves, so that might mean you get different keycaps from what you might expect. IIRC blanks that come on the otaku boards are coated, while blanks sold separately are non-coated (or the other way round, you get the idea). Still, blanks for a 5-pound surcharge are fine by me - so much so that I bought one and may buy another.
It's a little different for me - I need Hungarian layout so I don't get blanks for the looks. I actually put stickers on mine so I can find numbers and symbols easier, so it's not blank anymore.