Look in the Materials section under Resources to locate where you can buy nitinol (It's listed under Shape Memory Alloy). Unfortunately, the retailers listed are all in the US.
As for applications, I would contact the members in the previous discussion regarding Nitinol. Nitionol is a little tricky to work — you will need to do a lot of experiments with textiles, nitinol and your power source to get the desired results.
Typically, when you run a current through the wire, it heats up and contracts (or goes into its formed shape) and when the current is removed, it cools again and returns to its relaxed state. Nitinol responds to heat — either a current running through it — or you can use a hair dryer.
That's the basics of shape memory alloys. Shape memory alloys have various transition temperatures. Make sure you look at the technical specification before purchasing your wire.