Re: A New Sax
I've seen some great advice from others on this subject. You should check out other posts.
For my opinion, I'd get the best vintage horn I could afford - and that's what I did 8 years ago. Selmer Super Balanced Action is what Paul Desmond played. Selmer Mark VI was used by Lee Konitz - just to mention a couple of great jazz alto guys. Other pro-line vintage horns to consider - imho: 1930's or 1940's Conn 6M; Buescher Top Hat & Cane; King Super 20; 1940's or 1950's The Martin Alto; 1930's or 1940's Selmer Balanced Action and 1940's or early 1950's King Zephyr Special.
As far as newer pro-line horns, I've heard the recent Japanese major brands are good, and somewhat cheaper too - a nice used Yamaha 62 alto for $1800 for instance. You might also find a lightly used recently made Selmer Super 80 Series II for the same kind of price. I wish you good luck and good practice. TAKE PRO LESSONS.