Brad- that is one of the few NOT in my cartridge collection. Your best bet will be to check the auctions over at auctionarms.com, and gunbroker.com, and send a message to sellers of collectable cartridges. There WAS one on gunbroker, single round sold for $28 (CHEAP!) There is a 4.25mm Lilliput PISTOL for sale on GB- seeking $1250 for a starting bid. I have a single round of 2.7mm Kolibri, a 5mm Clement, and a .14 Alton Jones, but no Lilliput.
What we have here is... failure- to communicate.