Re: conn alto 1924
the older Wonder, New Invention and New Wonder Series I horns were a little fussy. These horns can be a pain to keep adjusted and to keep them in tune. Probably not a good choice for a high school student.
A Conn 6M would probably be the best choice, although 6M's usually go for more money. The 6M is built very well and is still considered by many to be one of the finest altos ever made.
The earlier Directors Model Conns with the shooting stars are good horns, and can be bought cheap. They're more of a student-intermediate level horn, while the 6M is a pro model (The 10M's little sister)