I think it is a 26 rather than a 26A. If you look at the frame line on the left of each stamp it appears to be continuous.

I'll defer to the experts as I have one of these 3c Washingtons that I'm currently trying to determine its type.
I can't help with retail value but a VF block of 4 unused of the 26 catalogs at $375 in the 2011 U.S. Specialized -- an unused block of 4 of the 26A is listed at
$5,000.