Anything for Tenor sax will be in the same key (just sound higher than it's supposed to on your Sop), and things like 100 Great Solos - no problem playing the alto versions of these unless you're trying to busk along with the original recording!
All sizes of saxes have the same written range, and Tenor and Soprano are both pitched in Bb, so all the music's pretty interchangeable. As for where to find it? Your local music shop should have a good selection, and there's always Amazon if you can't find one.
Nick