There's another totally weird thing going on with this stamp. There are dozens of listing for this stamp asking 200, 300 600 1000 and even $10,000 for a block of 4 when the next listing has one for $1.50.
Someone created a listing with RARE stamp and put a $200 price tag on it. Then the next guy saw it and listed another one with sky prices. Now there are @40+ listing with absurd prices. I nicely contacted a few seller and they both pretty much said they know nothing about stamps but saw the high price listings so they did the same thing.
Well I have a new theory. I think it is money laundering
Searching sold listings show these selling for $200-$1000. . I track trough to one of the sellers and they have lots of normal stuff listed and then a few different low value stamps at high prices. Another one seller has sold only one item - this stamp for $500 - with positive feedback!