I think the type of skis you get makes a big difference in how well you'll do out there. If you're going to be mostly at a groomed area then get skinny skis that will fit in the tracks. There's more to track skis than just the width, though. Do you want waxless or waxable? Are the conditions where you are mostly soft or icy? Depending on that you'd want a softer or stiffer ski.
If you're going to be out in the backcountry are you going to be cruising through easier terrain or going up and down the steeper hills? If you're going to be cruising than a medium width, medium stiffness, waxless ski is fine. If you're going to be pushing it more, step up to a metal edge for more control when you're traversing or turning. If you're going to challenge the steeps, you want a wide ski with a metal edge and probably skins for ascending. You'll want beefy boots and bindings for those skis, too. The conditions: powder vs ice, will also determine how stiff a ski you want.
IMHO it's better, when you're starting out to spend some time in a store with knowledgeable sales people so you end up with the best gear for what you want to do. It may end up costing a bit more than Craigslist, but you'll be happier in the long run.