Estate or antique/vintage? Estate really just means "pre owned" and can include recent styles. Those are easy to find in any estate shop or even a pawn shop.
If you''re looking for real antique wbands (diamond eternity or plain metal?) you''ve got to search estate and antique stores. Leave no stone unturned and go into any store that might have old jewelry.
Oh, and if you do a search on this, you should find some threads around here somewhere...