For people interested, I found out that a collapsable kayak is called a 'feltboote'. Looking for this on the internet showed me lots of options for buying multi-1000 chf kayaks.
As I am not a fat capitalist banker driving Maseraties and what not I decided to build my own from wood (not collapsable but hey, got to start somewhere) using the guide I found on http://yostwerks.com/ .
I am going for a 13 ft Sea Tour 13 as this size will still fit inside my car. Building cost should be around chf 200, I plan to buy everything at the Jumbo (wood for hull construction and PVC foil for covering). The foil for covering is 'teichfolie', foil for making a pond.
I've never kayaked before, never made such a complex wood-building project so it'll be lots of fun, plus I get a change to use my new (99chf) electric jigsaw