Whether or not you should buy depends on how often you will get to ski. If its only going to be for a couple days or just a one week trip you are better of renting. A lot of bigger resorts are renting park skis nowadays but twin tips aren't essential for skiing park. If you can go often, then buying skis might be a good idea.
Renting has a lot of conveniences, they wax your skis for you and if you don't like them you can exchange them for a different pair. If you have to travel with your skis it is much more cumbersome to be carrying skis around with you all the time and they take up a lot of room in the car. Also, remember that if you're going to start hitting rails, your skis will wear out quickly and you will need a new pair every 1-2 seasons, some people even go through multiple pairs a season if they're hitting a lot of rails.
As for skis, i'd check out the Line Celebrity, if you don't like the girly graphics, check out the Anthems and Chronic Cryptonites, all three will perform well all over the mountain and are a bit wider for better floatation in powder. There are plenty of other good brands out there though so don't commit yourself to Line, do some research, read reviews, etc.
Women's skis are specifically tailored for the female physiology so you will probably find they perform better, plus they come in smaller sizes, since you said that you're 147.
If you've still got some growing to do, I would wait it out a couple years, its not really worth it to get a full set up because its going to cost so much to replace everything. Boots can be expensive and if they start to not fit anymore because your foot has grown, you're not going to have much fun, trust me. If you live near a resort or will have the opportunity to go skiing often and you are truly passionate about it, buying skis could be worthwhile, otherwise, just rent.
