At one time this comic was thought to be one of the rarest Western Publishing comics (Whitman imprint) with less than 100 thought to exist today. The numbers have been
revised a little since then but this is still thought to be very rare.
In mid-May 2014, the CGC census recorded 9 gradings of these comics, with the highest at CGC 9.6/NM+ (Near Mint Plus).
Interestingly, #192 of the series was never printed (most price guides note this so hopefully there are no collectors out there looking for it!).
A copy of #191 (for sale in May 2014 grading CGC 8.0) went for only $100 hence a raw NM copy should, in theory, be more valuable but it is hard to estimate the price with any accuracy plus it can take
a little competition (demand) at the time of the sale to drive the final value up.
Full list of rare Whitman comic books featured on the website: