Many well-known musicians of all genres offer royalty-free samples via
CD for composers, musicians and so forth. Generally these are
extremely expensive - averaging $75 to nearly $200 per disc.

SourceCodeX (not so well-known) now offers ~~~Alien Ambience~~~ at
"starving musician" budget price for your use. You get 100 high-grade
wav files of 610 MB total running 18 to 60+ seconds each and a
6-minute bonus track is included.

More info & demo clips he http://sourcecodex.eer-music.com

Current sales listings:
http://members.ebay.com/aboutme/jazz_fusion_guy

Example of item for sale:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3766543436

Thanks for all the deep drones inspiration . . . you know who you are.
~SourceCodeX