Backcountry gear is an investment... There is a lot to get to properly be set up for backcountry missions. Most likely starting out, you will be doing shorter approaches and less technical skiing.
First off... Beacon, probe, shovel, first aid kit and educating yourself (take an aiare level 1 course).
As far as skis, boots, and bindings, you can go a number of ways.
Determine what you really want to focus on: making things easier on the way up, and keeping the descent more straight forward skiing... or dealing with a little more strenuous ascent, and having the confidence to jump off stuff and ripping more mixed conditions that most likely have smaller consequences than true ski mountaineering. It comes down to how important saving weight is to you for easier ascents vs. charging on the way down with the confidence in gear that could be skied inbounds. The more time spent on approaches and getting more vertical in a day the more you appreciate saving weight.
Depending on which is important you can go with an AT setup that is similar to a regular alpine set up...ie bindings like the Salomon Guardian (what I have been using), the Tyrolia Adrenaline, or the Marker Duke (I don't like it, solely based on having to un-click to switch in or out of touring mode). These are heavier and don't tour as efficiently as a tech binding setup. I can ski inbounds with confidence on any of these when avy danger or a change in plans puts me at the resort.
The other route is going with tech binding which will save weight and tour much more efficiently. There are now more rugged tech bindings out and more in the works to help bridge the gap between options. There are a lot of options now in this category and its worth talking to someone at a backcountry focused shop to get informed of the pros and cons of all the choices out there.
Boots, as with all, skiing will be the most important part. If you go with tech bindings then you most likely will go with a true AT boot. There are beginning to be better options for AT boots that still charge, and next year there will be several more options coming out to bridge the gap between weight and performance.
If weight is less of a focus there are several options of downhill boots with a hike feature that tour well enough and charge on the way down. A couple even offer tech fittings...ie tecnica, K2, and possibly salomon/atomic next year (i think, can't recall right now).
No matter what route you go, take the time to go to a good shop, that will work with you to dial your boots in with you...its a process for a good fitting boot that will perform for you.
As far as skis, there are all kinds of great skis out there. Just keep weight in mind, and what type of skiing you like to do. Coming from park, if you will be trying to do any switch riding get something with dual rocker... but not too much, because the more rocker the less ski on the snow and the less grip you will have for skinning up. I have both and prefer to tour on my Dynastar Cham 107 HM over my Armada Magic J (I use this when I'm out on my sleds) due to weight, grip on steeper inclines, and much easier to kick turn. Dual rocker is better for playing with terrain, while flatter tails gives more stability when charging.
Next year there are a tons of lighter weight focused skis dropping from almost every brand.
Outerwear really does make a difference... Some light weight, breathable shells that you can layer under make it much more comfortable when working up a sweat and then getting chilly on a windy ridge or peak.
Down the road you can look at airbags, gps, ice axes, crampons, snow saws, avy tools, etc if you are doing more than simple backcountry.
Hope this helps. I can't stress the education part enough and making sure you are out with people you trust. The mountains can be unforgiving, but also the most amazing, peaceful place to explore.
