I know, I am absolutely amazed that with all the fans out there, there's no real record that's easy to find.
Not even Wikipedia has a list (but it does of living dead dolls).
I can not find a complete list for the life of me, so I just piece together bits, mosty stores.
It looks like the first series by Moore was released in 1999?
When I want to research a Buffy figure, I rely heavily on figure realms database for the older figures, but it's faulty and incomplete, especially since it doesn't separate Moore and the Diamond Collectibles waves http://www.figurerealm.com/FiguresListChk.php?SID=44
and for the newer figs, Time and Space Toys http://timespacetoys.stores.yahoo.net/bufvamslay.html. They seem to carry all the newer figs and exclusives, just messed up a bit. Also, they don't pull the pics down after they're out of stock, so it's a nice history.
The Big Bad Toy store also has nice categories, so you can see who the distributers have been http://www.bigbadtoystore.com/bbts/menu.aspx?menu=157.
Diamons Select toys has some, but only seem to show the ones in stock that they're now carrying http://www.diamondselecttoys.com/.
And the Moore database is long gone.
If you find a near complete database, let us know!