A brain and training is the most important thing, all the best gear in the world is not going to do shit if you don't know how to use it. It may seem intuitive sitting in your warm and safe house but having to find a buried buddy is a whole different story. GET YOUR AVY 1 OR AT
LEAST do a lot of beacon practice with experienced friends. Until (and even after) you know your shit keep it mellow and safe and ALWAYS go with people who know what they're doing.
As far as gear goes you'll need a beacon, shovel, probe, and pack. Avalungs and ABS systems are useful but not absolutely necessary. There is absolutely no reason to get a send only beacon. Any digital 2 or 3 antenna beacon will work, the best beacon is the one that you know how to use, but it's worth it to spend a little more money and get a nicer beacon (for example 3 antenna beacons are more accurate). Don't get a single antenna or analog beacon.
Most companies sell packages with beacons, probes, shovels, and sometimes packs. BCA's basic package is probably the cheapest but the tracker DTS isn't the greatest beacon. While BCA is most likely the cheapest and makes good gear orthovox and mammut tend to make a better product. I'd check out their packages first and see if you can afford them.
Again get some training before you go into the BC and always go with people who know what they're doing!
