Trumpet player here. The problem with buying an older used trumpet is you have no idea how it plays unless you have a player test it. When Trent Austin's store was around here, I know of a trumpet player who helped a friend find a horn for his son, and he test played about 20 Bach Strads and came out with ONE that was a real "player" (I've played it, it is a great Bach.) There are Bachs that "fight with you", this is well known.... Many horns are played hard and hung to dry as they say, and need a valve replating that costs about $400-700 these days. The issue is COMPRESSION. That's an important word in brass valve land. Players even get a valve alignment job, there are people (techs) famous for their alignment ability. A newish horn is a tight and adjusted horn. A horn with worn valves is fixable but it's as unplayable as a bass with a bent neck and broken truss rod and discourage the student.
There are LOTS of recently built and gotten rid of horns in mint condition around. Trumpetherald marketplace is Great and the people are great. In your price range I recommend a mint but a once used Carol Brass trumpet. They are as good as a pro Yamaha or most anything else, there are different bells and materials (more or less copper from yellow brass to gold brass to red brass to copper coated...) different bells using Bach's bell standards either a 57 (med) or the Bach 72 (large) and a choice between 2 shapes of tuning crook, Bach shaped D or more of a smooth curve like modern design trumpets, makes for less resistance and darker sound. Carol Brass are made in Taiwan, and somehow they've made a great playing almost custom instrument for less than half a Yamaha. (and I'm a Yamaha player, my (rebuilt valves) late 80s 6340ST is still the lead horn to beat in a brightness competition, but I'd have to get 1600.00 (which is piddling compared to other new pro horns, 3800-8000 is standard)
The Yamaha 203 WAS a great horn, then they changed it for the student market, the 2030 present student horn just isn't worth the price. Used ones are apt to be beat up, I wouldn't buy without trying.