And then a little secret. The best play to find old, heavy, cracked and otherwise interesting finials is secondhand. Rip them off ugly lamps, scour the internet, search eBay regularly, dig them out of the trash! Some of my finials were seriously a steal. A cursory search on Ebay and then Etsy yielded these:
Left to right: Etsy,ornate brass finial from myohmymaggie, $12.00, Ebay fleur de lis finial, Etsy porcelain rose finial from mothtoaflame, $32.00, Ebay ruby glass finials, Ebay amber glass finials, Ebay tole flower finial.