Hi,
You might want to try the guys at "One More Tandem" (
onemoretandem.ch). Its a second hand sport shop that has a large range of bikes and other sports equipment. It is located up behind the Olympic Museum at Ave de Montchoisi 49, Lausanne. Last time I was there I noticed they had a couple of folding bikes.
Pierre and Jo both speak very good English (and French and German) and are very helpful.
Cheers