This place has them for sale
http://www.tokyofixedgear.com/shopdi...Complete+Bikes - seems they have two small-wheeled mini-velos; the Cycroc and the Bruno Ventura Flat - both very nice but a bit pricey.... A good starting point though? Don't forget a non-seperable Moulton is basically a minivelo too...
OR a non-folding Twenty- like my 24" wheeled beastie.
Bruno Ventura (Very nice retro)

converts to:
Cycroc
Moulton:
Raleigh Shopper
Old

New

Mine
Also google for : Pacific Reach, Cannondale Hooligan, F1 BMX frames...