Rocksuresoundz.com currently has 24 different sound packs in a wide range of genres, available at just $6-95 each. Each pack contains between 80-200 high quality sfx. Additional new packs will be added soon too.
There is a one and a half minute audio preview for each of the Sound Effect Packs.
Hitting the play button gives you a bit of a general overview medley of the contents of the pack. Not every sound effect in the pack is included in the preview, but it's designed to give a good cross-section of sound types found in it.