Nala,
In your price range, you've lots of wonderful used professional trumpets from which to choose.
The Bach 37 has a long lived reputation.
I'll put my 2 cents in for what I bought a year ago on Ebay for $680. A Selmer K-Modified ML 24b. Some Jazz legends played Slemer horns. I'd like to say "many," but I don't know that that is so.
I learned recently that Vincent Chicowitz who played 2nd Trumpet in the Chicago Symphony Orchestra for several decades used a K when he played a Bb trumpet in the Symphony.
Here's a great link from Jim Donaldson. He discusses many points to consider when buying a trumpet:
http://www.dallasmusic.org/gearhead/
Good Luck and Enjoy your Search,
Richard Oliver