Depends how you want to approach it... piece meal slowly (more expensive in the long run often times but rather cheap in the short run) or just sinking money into the whole thing. As an absolute minimum, you need a releasable heel, skins, telescoping poles, a pack, and layers. Trekkers are a short term cheap purchase but most people usually discard them eventually so it is more expensive to buy trekkers in the long run. You can get bindings that work with alpine boots (which I did for my first earned turn season) but doing so may limit you long term (e.g. I might be interested in Dynafit now that I am more experienced). Skins, get the good stuff and pay lots, don't skimp. Touring poles are about $60ish for something decent. Pack and layers depends on what you have. I would suggest a bare minimum of a $500 investment if you use alpine boots and deal hunt though you are probably looking at more.
I have some of the cheaper stuff covered (pair of indigo - epics poles that i got for $50 on SAC, pack, and layers). So that leaves skins and binding. I'd have to upgrade skis as well. Right now I have just 67 underfoot.
Any models of bindings or skins should I research?
Thanks for the info guys.