My wife has just started skiing. She's been 3-4 times. She's 5'9", about 140 lbs (who can know these things for sure?). She's very cautious and I don't see her developing into some aggressive bomber. She wants to be able to go out with my son and me while we fall down learning to snowboard. The rentals they've put her on were 140, 147, and 150 (though this last time, she said she didn't like the 150s and went back down to 140s). I think her perception of comfort on the shorter skis is generally related to her nervousness about skiing. As the day progresses each time we're out, she gets better and better and more confident (she can snow plow her way down any blue hill we've encountered here in Minnesota). She wants to buy some skis and get out of the rental hassle. We'll probably be going 8-12 times a year to very mellow hills (there are few other here). I think she should get something at least 150, but I can't crack the "but I like the shorter ones better" argument! That said, maybe I'm just plain wrong and she should get whatever size she feels most comfortable on.
Any advice on lengths and--for bonus points--thoughts on relatively cheap skis/bindings/boots that would be good for her is appreciated.