One of the worst things you can do is buy a cheap "student grade" horn, because they usually play so poorly it is impossible to learn how to do it right.  Names to avoid are Jupiter and Bundy, plus anything made in Korea.  Call Chuck Levins.  They are one of the biggest instrument retailers in the country and have a huge inventory of new and used at every price range.  I have bought horns from them over the phone and everything was exactly as they described it.  You should be able to get a decent used horn of good quality for less than the new price of a piece of junk.