Musician's Friend is where you would want to look if you are checking out musical instruments.
Their wide range of products include among others, guitars, keyboards and MIDI, drums and percussion, amplifiers and effects equipment, even books and sheet music and not forgetting brass and woodwind instruments, of course.
alto saxs at musiciansfriend.com.
If you are from outside of the U.S., don't despair, they ship internationally and to enhance your shopping experience, they are constantly adding new instruments. The site is easy to navigate. You can shop by department or by category.