I've done some searches on yahoo and other sites but they only seem to go to places that recommend the surf music and not where to buy any of it. I looked on Rhino's site and there were no albums to be found, which surprises me.
I have inquired at a local music store and they said a lot of that stuff is out of print, but I am sure there is somewhere on the web still selling it for a reasonable price.

Sundazed.com

I remember downloading a ton of "surf music" from emusic.com a couple years ago.

I just found out that the "Cowabunga" box set is OOP, I should sell mine!