Brickhouse Music- A local music store here in River Falls. I have been a customer of theirs for years, and I strongly recommend that you check them out!
Midwest Musical Imports - A great place to buy supplies for any woodwind instrument, especially double reed instruments. They're located in Minneapolis, so you can either order online or go over to the store.
Sheet Music Plus - If you can't find the music you're looking for locally, you can probably find it here.
Charles Music - An online music for the players of double reed instruments.
Forrests Music - Another online store with hundreds of double reed instrument accessories.
Advantage USA - An online seller of affordable single and double reeds.
Free Sheet Music
Free-scores.com - A wealth of free sheet music, both classical music in public domain and music by modern composers. Music for all ages and levels!
Petrucci Music Library - An extensive collection of classical music in public domain, for many different instruments. Just download the music and print it out!
Solo Vocal Music--ChoralWiki - Solo voice music that is in public domain and free to download and print. This site also offers free choral music.
Sheet Music Fox - Another collection of free public domain classical sheet music.
Free Popular Piano Sheet Music - A collection of popular music for intermediate-advanced piano, all free to download and print. This site also offers collections of classical, Christmas, Christian, and easy piano music, also all free.