Lucky Late Blue Amberol Find!

[redseal25]

I was antiquing on a trip to Rapid City this weekend. In the musty basement of an antique store was a big, dusty bowl of busted up blue amberols- shattered plaster galore and a few crushed black waxes. Amongst the junk cylinders, was Blue Amberol 5554 (Ramona Waltz by the Florida Four). To my immense shock, the plaster was intact with no celluloid cracks. When does that ever happen?? Ha! Best four bucks I've spent in a while. Thanks to Shaun O'Rourke's informative youtube video, I found the "Florida Four" is a pseudonym for Nathan Glantz's Quartet and it was released in July of 1928. My copy is take one, mold 3.
It has been suggested in other forum posts that the 5000 series were marketed mostly to the Southeast and some Midwestern states. That info squares well with this find and the only other late blue amberol I've ever found in Omaha.
Questions for more experienced members than I:
A: Roughly how many cylinders were produced of each title by July of 28? This one is on mold 3, so we know a few were made.
B: At what point did Blue Amberols become a mail order only business?
C: What geographic areas have other members personally found late blue amberols in the wild?
Thanks

[Roaring20s]

Nice find.

I found 30+ in Tucson at an estate sale, but do not know were the owner obtained them.

James.