Where to purchase a replacement tweeter?

I have a pair of old JBL's that are in need of a horn tweeter replacement. Any thoughts on where to find replacements? JBL no longer stocks the part.
Sagres, try zalytron.com if they can't help you, likely no one can. Good luck!
I often have to replace tweeters on very old speakers for customers.
Entering the tweeter part number or speaker model numberinto Google often pulls up inexpensive sources. Usually someone who has salvaged parts from busted speakers.

Good luck!
Thanks to all for the advice.
madisound or speakercity