Thanks for the link to the PDF file on meters. I'll have to read through that data which may help to answer a lot of questions I have on meter collecting.
Just curious though: What makes that 1935 cover so rare? Is it the cover itself? The advertising logo? The denomination? Or the PB meter imprint from Albany, NY?
I have a similar PB Meter imprint from NYC shown below (curiously this example uses no decimal point):

In fact, I have a collection of meter cuts from as far back as 1933 from various suppliers (i.e. NPM, CC, PB, etc.) and I've never quite gotten a handle on how best to collect them or what to look for in terms of rarities, so they sit in a box of glassine envelopes sorted by year.