My son has been playing the alto for 5 years now (just started sophomore year), and he's been playing on the same Armstrong model I used when I was his age. He's much better than I ever was, and has severely outgrown this old student level horn. I want to upgrade to something better for him, ideally something he can finish high school with, and even use in college if he chooses to continue academically in music. He can continue to use the Armstrong for marching, but needs something better for symphonic and jazz. Do we go with something like a good used YAS 23, which is still a student model but much better than the old Armstrong, or move up to a more intermediate horn? I'm leaning towards upgrading the quality, but need some guidance on what I should be looking for in that Intermediate range in a good used horn. Any suggestions on Make and Models of horns in that category and what I should be expecting to pay would help me limit my search. I have a 1923 Buescher Silver True Tone I can sell to help fund the purchase of the new one, but I'm not even sure on a value of that anymore.