Yep 12V DC (nominal, whatever you actually get in the lighter socket will probably be fine)

As to online sources for the parts, I have no resources at hand, but it shouldn't be very hard to source these things in any semi-large western city
The cig.adapter plug should be available at any auto parts store, and the plug that fits the empeg in any electronics store that sells parts (like Radio Shack for instance).
Cable - just about any two-conductor somewhere 2x0.75 to 2x2.5 mm2

I'm utterly unfamiliar with the Belgian situation though.

/Michael