Whenever I want to get an idea about what market pricing is on anything I use ebay as a resource. For example; http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

Whether or not you want to buy from ebay doesn't matter, it's a reflection of the market for price and availability, and sometimes you can learn about things you didn't know about. If you've never used ebay here's some searching tips. Don't just type in the search description in the way you first think of it. If I were looking for what you are I would probably search for
bb chev bellhousing
bb chev bell housing
bb chevy bellhousing
bb chevy bell housing
bb cheverolet bellhousing
etc.
big block chev......etc.
Then 396 bellhousing
and 427, 454, etc.
Then of course there's misspellings..........but that's way too much of a pain in the butt to play with.