Now we know it's a fake. That is far too low for a genuine example.
Hardly the go/no-go test for genuineness.
I have successfully purchased Series 1940 overprints mis'IDd in eBay
collections because I knew what to look for, and others didn't or didn't pay attention.
The fact I purchased them far below cat doesn't mean they aren't real.
In this case, folks were skeptical and didn't bid.
I withhold opinion as I don't collect these, but final price shouldn't be what determines whether it is genuine.