Since catalog listings are suppoed to be from
the actual retail marketplace and what you are seeking,
and in this case finding, is by definition an item
that is both not a postage stamp, as well as
being virtually never seen in the retail stamp market,
( At least I've never seen an example.)
I suspect you will not get a valid "value",
retail or otherwise, unless by some chanmce
someone has created an updated specialized catalog
just for that type of item.
It is however an interesting item and
there may be an interesting story
behind its creation.
From time to time I pick up a few stamp proofs in my endless search for interesting World Wide stamps. Recently, I acquired what appears to be a "proof" of the Croatia SC#B35 stamp. The stamp (proof or partial image proof) is imperf., with full gum and hinge remnant. Is there any way to establish a catalogue reference or valuation to stamp proofs, such as SC#B35?
re: 1943 Croatia "Proof" SC#B35?
Since catalog listings are suppoed to be from
the actual retail marketplace and what you are seeking,
and in this case finding, is by definition an item
that is both not a postage stamp, as well as
being virtually never seen in the retail stamp market,
( At least I've never seen an example.)
I suspect you will not get a valid "value",
retail or otherwise, unless by some chanmce
someone has created an updated specialized catalog
just for that type of item.
It is however an interesting item and
there may be an interesting story
behind its creation.