Where do antique dealers find the things they sell?  (For example,
estate sales, auctions, etc.)  Can you think of any other places or
antique sources?  I am looking for a comprehensive list of the types
of places a professional antique dealer would go to, to find antiques.

Furthermore, I am interested in where lists of these specific
place-types can be found.  For example, if a buying source was an
"estate sale", where can I get a list of estate sale companies? 
Please be detailed and specific.

Any help is appreciated.

Here in the UK, we have 'door knockers' who go from house-to-house, speculatively.

We also have burglars who reputedly 'steal to order'.

I've used http://www.chinafinders.net to get some interesting
collectibles. They ship worldwide and are really reliable.

If you need antiques manufacturers address from India, let me know