There are several factors that impact the final value or selling price of a comic book. Most people are aware of the importance of the title (usually the focus) character, the issue number (say #1), the grade or condition, and any important events (for example a new character intro or origin). One other factor you should be aware of is the artist who worked on the issue, and if it is a famous example of their work. For the most part artists fall into the nameless category and there is no impact on the the value. But for specific artists the price of a particular comic book issue can change significantly. Let’s look at a recent sale of a Contact Comics issue as an example.
In the January 31 Heritage Auction a Contact #11 CGC 8.5 (VF+) sold for $239.00.
But a Contact #11 CGC 7.0 (FN/VF) sold for $896.25! (See the issue here)
Why would a later issue in lower condition sell for such a premium? The artist with a famous cover! Issue #12 has a cover by L.B. Cole that is noted as one of his most interesting. He also was part of #11 but for whatever reason the science fiction cover of #12 is more popular.
The lesson here is a particular artist can have a great affect on the price of a comic book. Look for first artwork, generic work, and “famous covers” from the artist for issues that rise above the usual prices.