Where to find Leopold FC660C-compatible keycaps?

At the time of my purchase for the Leopold FC660C (i.e. Topre variant), the laser-engraved PBT keycaps were the only keycaps available for the keyboard. Now, Elitekeyboards has a newer model with dyesub PBT.

Since Elitekeyboards doesn't sell the keycaps individually, I was wondering if you guys might know where I could get my hands on FC660C-compatible keycaps. The layout is, after all, a little awkward.

Suggestions?