I know Alana pointed this out a while ago, but in case you missed it, Peach Momoko has a story (not just cover art) inside Heavy Metal #299. Her first Heavy Metal Interior work was in Heavy Metal #288 which goes for $100 or more and her second interior work in Heavy Metal #290 is a $20 book. With Momoko being hot this could be a good grab.
(Thanks again to Alana for the info)