I seem to recall someone (Peter David?) talking once about how unfair it seemed at conventions that the artists could go to the hall and make 20 bucks on the side doing a quick sketch, and proposing that the writers might be able to dash off a paragraph or two about a topic a fan might suggest so that they also could ride that cash train.
But to your point--the last news I heard had artists at, conservatively, around $75 a page (a lot of this is based on the title and the artist, so this figure is only based on my personal experience.) Writers have been known to charge as little as $20.99 for a single issue.
Sr. Editor The Trades
: Entertainment industry analysis since 1997