misprints are NOT always worth more. depends on different things. also their worth is what a person is willing to pay for them. oddly enough my favorite era of comics 80's isnt worth ass much as some of last years comics. take the dark phoenix saga for example. a HUGE series back in the day. now i could have gotten the whole series for cheap at the last comic con i was at. (yes i go to comic cons people what of it :-)) depends on what you have and condition. now dont get me wrong if you have amazing fantasy 15, umm incredible hulk 181, or say tales of suspense 39 yea thats worth money. if i was closer i would give you a hand. if you want you can catalog everything you have and let me know. i can then go thru and tell you some key issues that may be of worth. although again it depends on condition. also how are they kept? are the boarded and bagged? or are they just loose?? oh yea and a lot of the prices guides are not worth a dang. the big print books are not too great. you can pick up a issue of wizard though. its a good ballpark guide. in the end though its what ever you can get out of em. sometimes more sometimes less.
p.s. hell i have a 85 300z sitting in my driveway i might trade you for em. it dont run though.
edit: i will try to think of some good 80's comics that would be of good worth. umm the drug issue from spiderman would be a good one. gambits first appearance was in the 80's. i will do some thinking and see if i can throw together a list of good ones to look for. i say 80's because the new muntants 51 you mentioned i think was in 87.