Before even starting, just check with the school. Some schools require you to have a specific make/model instrument. You can challenge it, if you get a better horn than they require, but some schools are, well, stupid when it comes to this.
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First, even though he's the 'site sponsor, he generally has good horns at good prices. So these numbers are from Quinn the Eskimo. If you end up buying from him, mention my name so I can get a discount. Call or e-mail him. He probably has more stuff he hasn't listed on eBay yet.
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New Yamaha 480: $2749 (intermediate-class, from WWBW)
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New Yamaha 62III: $3275 (introductory pro-class, from Quinn)
Second, if you're looking for a new horn, you might also look at the Yanagisawa 901. They're only $3099 and are also introductory pro-class. Feature-wise, it compares very favorably to the YAS-62III. Maybe even a bit better.
Third, I don't see any compelling reason to buy
any horn new. I wrote a
rather long article on my blog, where I recommend older pro horns that you can get under $1000 (for alto; say, under $1500 on tenor).
And then there's eBay:
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The YTS-62 that saxhound links to, above, is all of $100 more than a new YTS-480 and it's overhauled by a good store. It's arguably not as shiny, but you can't play the shiny.
* Quinn's got a Yamaha YTS-875EX -- that's a top-of-the-line custom, pro model --
currently selling at $675. It's not new, but it looks perfect. You could easily get lucky on this horn and get it for under $2000. Not a lot of folks are looking for these, but the 82Z.
* Quinn's got a nice looking, late model King Marigaux (a stencil from SML)
that's all of $2080. Again, a very good pro horn less than a new intermediate horn.