I just picked up this 1/2-d John Ash gutter imprint pair and I'm happy with it. Okay centering, considering. I believe the underlying stamp is SG124, issued Feb. 1933.

The values of these imprint pairs seems to be all over the board. Any guess as to a potential value of this one?
In particular, is there a reason that this one would be less desirable than some others?
Thanks.