Matthew, one other thing that might prove helpful - I don't know how well the Comichron site search engine works, but I've found that a Google search like this:

"est. preorders" comichron plastic man 1 archives

...will often take you to the appropriate Comichron page like this:

Comic Book Sales Figures for December 1998
www.comichron.com/monthlycomicssales/1998/1998-12.html
Search for comics sales figures on Comichron! Enter the title ... Comic-book Title, Issue, Price, Publisher, Est. preorders. 1, Witchblade ... 19, Spider-Man Chapter 1, 4, $2.50, Marvel, 71,920. 20, Mutant X, 5 ..... 5, Plastic Man Archives Vol. 1 HC ...


So there's one number I provided earlier that you can verify.  Hopefully, they'll all be that easy.