Instructions
Contact the publisher of a comic directly. The publisher is the source directly responsible for the comic and will have the most detailed information about the issue. The publisher may not always want to share such information, however, and may have its own financial stake in the matter.
Research one of the publications or websites that track comic book prints, such as Comics Buyer's Guide or Comic Chronicles (see Resources). These organizations do a good job of tracking comic book sales and print runs. File through the back issue and catalogues in order to find out as much as you can about the actual print run.
Locate a comic specialty store. In addition to having information about publication print runs, the specialty stores may also know how many copies of a certain issue are in circulation, which titles are out of circulation, and which ones are likely to be brought back into circulation. For example, the first printing of an issue is always going to be more valued than a second or third printing of the same issue.
Find a collector at one of the larger comic conventions in the United States. Some of the rarest and most sought-after comics are frequently presented or sold at these functions. The San Diego Comic-Con convention is the biggest such event in the world. Wizard World Chicago (formerly Chicago Comic-Con) is next. Baltimore Comic-Con is the third largest convention in the United States.