There isn't much useful we could tell you. Most of the "bikes" in that price range are going to be bike shaped objects rather than something you actually want to ride. Do you know someone who is handy with tools and such? If you buy online you might be able to get something like the Dawes SST steel from BikeIsland if they have it in your size. The Schwinn Cutter is at $167 from CityGrounds. But you would probably want to take them to your local bike shop to get them built which could add to the expenses significantly.
Make sure that you know the size that you should get. You can use a
fit calculator and compare the results to the size chart of what you are looking at but you are probably still growing so it might be best to err with getting a bike that is too big.
Europa was right that the best thing to do would be to go to an actual bike shop but unless they happen to have a trade-in or something it is unlikely they will have anything in your price range. Do not buy a Thruster from Wallyworld or whatever that thing is that they are selling at Target. You would be better off buying something on-line. Good luck.