Soaking:These stamps,
which I think are 2012 printing issues or emissions, referring to the date (from the stamp above) on the lower left side of the stamp:
(121105 = 2012 11 05 = Nov 5, 2012)?? (see below);do soak off in warm water very easily within
10 minutes (oops - see next line) or so, with just a slight trace of self-adhesive gum left floating in the water.
However, after some soaking of other stamps and trying to remove the remaining adhesive by rubbing with my fingers in water, I ruined a few stamps and even crinkled them up a bit.
So,
20 minutes of soaking in warm water and
No Rubbing is now recommended. Even collectingthese stamps on paper would be a recommenation by some I think.

edit addition:

After consideration I think the numbers in the photo of the butterfly are from the original photograph of the butterfly, and not from the stamp printing company.
Three other different ones are drying in my Desert Magic drying book as I type.
Availability is good also, found on
ebay somewhat but mostly, so far anyway, on Delcampe from European sellers, maybe in kiloware abroad.
Priced at 99c or less for a single stamp or envelope. Price can go up to 5.00 Euros or more for a mint stamp or nice envelope.
The shipping is always a factor of course and varies from seller to seller.
edit: typos and added text.