If you live in Utah, go to the Black Diamond's bi-annual outlet sale. I bought my Avi bag for like $400 with the battery pack (typically retailing $1200). Otherwise look for end of season sales you'd be surprised how cheaply you can get them with a little strategic sale shopping.
As for do you really need an airbag? How sure are you of the stability of the snow pack beneath your skis, and above you? Enough to put your life on it? Because essentially that is the gamble. Not to be the asshole.
If you are not going to drop money on a bag, make sure to have at least a beacon, shovel, and probe -- as well as anyone else with you in the backcountry. Most importantly make sure your friends have a good shovel -- because you are not going to dig yourself out. If their shovel looks tiny, give them yours for the day. Practice beacon search regulary with your friends, how to find someone with a probe and dig them out. Because its not intuitive and when under a crisis situation it will be even less intutitive. There are a lot of cheaper one-day courses you can take for your first year and then really invest in an avy 1 certification. The knowledge and understanding will pay off.
http://unofficialnetworks.com/2017/...urial-in-utah-broken-legs8-minutes-submerged/