Tips about ski-randonne (back-country) equipment

Hi,
Anybody could explain me what I need to buy for back-country skiing?
I am new in Switzerland and I would like to have my own equipment for skiing. I never did back-country skiing but I would like to do it, better than normal skiing in slopes. So I thought of buying equipment for it, cause I have been told that I could use it in the slopes also.
The problem is: I wanna buy it second hand and I am quite lost about what I need to buy. Any tip?
I looked for boats and I could find some quite cheap, but it seems that each boat needs a different ski (or the fixation)… So…well, any tip of what I need to buy???
Thanks!!

Basically there’s two kinds of bindings: Dynafit-compatible (sometimes called « Tech »), and most other bindings. Most other bindings will take any « standard » Alpine Touring boot. Dynafit requires a boot with special metal fixtures. Most modern boots are Dynafit-compatible (but you have to check, if you want that).

Then after you purchase skis with a binding on them, some expert needs to adjust the binding to fit your boots correctly. The binding has a limited range of adjustment (tends to be smaller range on Dynafit-compatible), so it might not be possible to adjust the binding to fit. So need to check this size compatibility before you purchase both binding and boots.

Ken