Adam from Poison Props does some amazing sound effect CDs you can purchase. Otherwise the folks at Gore Galore also have plenty of great tracks of their own as well as other talented artists on their website HauntAudio.com.
Otherwise there's always of course Midnight Syndicate or Nox Arcana which offer some great ambiance.
You can purchase parts of certain albums and burn everything to a CD or get yourself a cheap MP3 player or iPod to run your sound off of.
I wouldn't suggest...
I have heard of California haunters having a hard time locating it as well. I believe this is due to the product being illegal to use in new buildings. (The stuff gives off a nasty gas when burned.)
What you might have to end up doing is crossing state lines and locating it elsewhere.