Sorry, Michaels is a US craft store chain. Didn't quite know where you were in the world!
I have two models, both from Michaels; one runs on two D-cell batteries (much larger than those used by the unit in your eBay link) and the other that plugs into the wall. They ran about $10 and $20, respectively. The D-cell unit actually cuts better because it uses a thinner wire, but you can't use it to, say, cut a two-foot-wide foam board in half, because the U-shaped arm that the wire is tied off to gets in the way.
The plug in unit has a thicker, stiff rod for a blade, but I broke mine early on and had to use a spare hinge and nuts-and-bolts to make a splint for it. It's good for jobs where the arm on the battery-powered model would get in the way, but I prefer using the battery model for sculpting hills and things.
Here's some do-it-yourself ones:
http://www.instructables.com/id/Hot-wire-foam-cutter/http://www.instructables.com/id....availabI think you could take a woman's curling iron and use that as the base unit, or a flashlight as Lotus said; just get a thin wire that will heat up well when current goes through it.
