So awesome to stumble across as avid of a Moon Knight fan as myself. You've got quite a collection going. I may have you on shear volume of copies (I'm approaching 5 complete runs of each of the series and almost 10 copies of WWBN 32 along with a full run of WWBN), but you far surpass me on random appearances, etc.
Anyway, the difference in the price markings you mention are direct sale versus news stand. IIRC the diamond is the direct sale version (comic shops, etc) and the other is the regular news stand.
Anyway, awesome work! I'm now going to use your list of appearances to complete my collection as well! Moon Knight is essentially all I collect for the same reason you seem too. Thanks for the inspiration!
edit: I'm always on the look out for original MK art, especially from the BillS days. PLEASE drop me a line if you see any!... Also, I started collecting LONG before the CGC ever existed. Whats the best/easiest way to get some of my MK books graded?
edit2: You would probably appreciate this MK original art. I've been trying to get the owner to part with it for a while now..
The image itself is too big to show here: Moon Knight Original Cover art