None that I know of. And plenty of Spacers have advertised in the past.
PS. Oh, and on the topic of advertisment: There are a number of free methods you might want to try as well. These include registering on sites like the <a href="http://www.belfry.com/comics/">Belfry</a>, setting up a keenspace newsbox, and putting your comic's banner in your forum sig.
PPS. This really belongs in the help section. Gear is for sharing "tutorials, utlities, tips and hints [on] using KeenSpace."