While I tend to agree that the Ditko superhero stuff is his most pricey, I don't know if you can place Dr. Strange far behind ASM. While his Strange is behind ASM in popularity, his output on Dr. Strange was very small compared to his ASM output.
Ditko produced approx(pencils and inks) 828 pages for Amazing Spider-Man,
Ditko produced apprx(pencils and inks) 298 pages for Dr. Strange.
Most of the Dr. Strange stories were either 5,8,9 or 10 pages each with none being longer than 10 pages. Ditko's ASM stories were all at least 20 pages in length. So while Spidey might be more popular than Dr. Strange, he also has a 3 to 1 lead on all Ditko pages that were produced.
If the supply were equal I would agree with you ASM pages and Dr. Strange pages of similiar quality would be ASM #1 and Strange #2. But the dearth of Dr. Strange pages in existence and the rarity of quality pages to the market close the gap considerably. For similar in costume action pages I have seen Dr. Strange pages be the equal to sometimes, and at times the superior of, similar quality ASM pages....and that is do to simple relative scarcity.
The rest of what you said makes sense.
Best,
Chris Caira
That's a great point Chris. Ditko ASM pages are not all that difficult to find if you have the $$$ but Strange Tales pages?? Very tough.