Distinguished SOTW Member, Forum Contributor 2014
Super Action 80 Tenor, Buescher 156 Tenor, Yamaha Vito YAS-21 , Kessler Soprano, Superba II Bari
Bingo.Another reason to buy a used horn for a young player is that should they quit... and most do... you can sell the horn for basically the same value paid.
Best bet would be to buy a used Yamaha. Great horns in their own right, and easy to find. $600 to $700 is the average price for a used one in good condition. Use the rest of the money to find a good player in your area who can play test the horn, and teach your son.
BTW, why tenor before alto? That's a lot of horn for an 11 year old. Heck, alto was a heavy horn for 10 year old me, and I wasn't a small kid. Just something else to take into consideration.