Take your time selecting a bow. Most good ones start around 300US and go up from there. Some new experimental types are made out of things like graphite and fiberglas and get good reviews. No matter how much you pay, and how much good advice you get from members of this site, you will have to try many bows to find the one that is right for you.
Katie, have you tried cleaning your bow hair? I had an old pernambuco bow that I was sure needed a rehair, but a good cleaning took care of it. As long as the hair hasn't thinned, I would try cleaning it first. My cleaning technique is to curl up the hair in a little bowl and cover it with rubbing alcohol. (Make sure to keep the stick and the frog out of the alcoloh.) I then gently scrub the hair under the alcohol with my fingers, and let it sit for an hour. Carefully remove the hair and dry with a paper towel or two. Let it set for about 15 minutes before putting the bow back together.
Regarding new bows, I highly recommend the Coda Classic. I bought one used for $450. It really helped my bowing technique by making my shortcomings evident. I became a much, much better fiddler in the course of two weeks. I don't ever intend to go back to wooden bows.
Edit: fixed some typos. I can't believe what a dreadful speller I've become.
Bows are not all expensive. I have two. One I paid $ 29.95 US for and the other one was free. Having said that, I will say that I probably need to upgrade my bow. The problem is I don't know enough about bows to make an intelligent decision. The way I play it probably doesn't make much difference. I would probably end up paying several hundred dollars for a bow worth $25.
I never will be real good, but, I ain't as bad as I was!