Definitely get your avy knowledge up. Best way to avoid getting killed in an avalanche is not getting caught in one in the first place.
As far as splits go. Yeah, they are expensive. Check the splitboard.com swap forum
for people selling splits. Boards your size pop up here and there in the DIY mode. Prior makes decent riding decks, but they do seem to run a delamination problem with their decks. A high number of them seem to delam by the end of the season. It seems like every year someone on sb.com complains about it.
I really think the women's market has been left out in the (no pun intended) cold by snowboard manufacturers. You are not the first women to say this. I've talked with Vman about this at some detail. I think some company is going to move on it in the near future. The sport is blowing up too much for someone not too.
Also, I wouldn't discount out something like the Voile 154. It might be a bit of a boat for you, but keep in the mind the general rule of thumb is that you can ride something 6cm longer than your resort deck for splitting. Deeper snow, more float, etc.