Jim's Cameras - Seattle: $11.00 per spool.
http://www.jimscamerasseattle.com/620filmspool.html

Below, a list of used camera suppliers that I have used in the past.
Some items may not always be listed on their sites. Call or Email.

Blue Moon Camera & Machine - Portland:
http://www.bluemooncamera.com/http:/...ooncamera.com/

Glazer's - Seattle:
http://www.glazerscamera.com/store/

Pacific Rim Camera:
http://www.pacificrimcamera.com/

Midwest Photo Exchange:
http://mpex.com/

Marc