It depends on the music publisher you're getting the sheet music from and what genre of music you're looking for (like marching band, jazz, etc). Call the publisher and ask for a catalog.
My guess is that your question is asking where free sheet music for the alto sax can be acquired, there are several resources on the world wide web, which is easily search able, but the most popular by far is 8notes.
Often you can get the very latest music, since some composers post their work online.
pdfdatabase is a good source too, as is Petrucci Music Library-google for the addresses.
