No, but I've bought many lots of comic books. The store I worked at only really bought large lots of comics unless there was something special in there. At the time, we got our prices from the Overstreet Price Guide and its monthly updates, but I think that everyone's pretty much moved to Wizard prices since they put the Overstreet monthly updates out of business by inflating their listed prices so that more people bought it so that they would feel better about their collections. Since then, Wizard has become much more respectable, since they're the only monthly game in town, but still somewhat pandering, IMO, but some shops will still probably go by Overstreet for older stuff. You stuff is probably right on the borderline.

Anyway, we usually purchased lots at about $0.50 on the dollar, give or take some depending on the desirability of the comics. Of course, that was after we graded them. Comics prices drop dramatically if there's much damage at all.

If someone came in with a handful of comics or less, then we wouldn't usually bother buying them unless it was something we wanted, which could vary from whether we simply didn't have any of that particular issue to only if it was a highly desirable comic, depending on what business was like at the time. If we were buying lots, we just took the whole lot, whether or not we wanted the individual issues. Unless it was just a load of utter crap, in which case, we might pick and choose if there were a few good things in there. What crap is is going to depend largely on the store. Of course, some crap is always crap. Vertigo is probably of the sort that's not too interesting to some shops, very interesting to other shops, but definitely not always crap.

I will have to note that we were very reputable as far as comics shops go. Many shops are underhanded. I'd definitely make sure you have a good idea of the value of what you've got before you take it in. I'd also suggest that if you have some that are particularly valuable that you pull them out of the lot and sell them by themselves, even if it is just to the same store, as you'll probably get more for them that way than if they were just mixed in, and that wouldn't even be especially underhanded. It's just that if you have, say, a Sandman #1, then you're going to get 50% or whatever the lot percentage would be if it's in the lot, but if you sell it separately, then you might get up to 65%, which could be quite a bit if it's still about $50 in mint condition.

Check out this grading guide; it's pretty good. Assume that the numbers in brackets next to the grades are one-tenth the percentages of what's listed as the price in the price guide. That is, if you had a book that you judged to be very fine, which is listed at 8.0, the price that the shop would try to sell it for would be 80% of what's listed in the price guide.

HTH. Let me know if you need more info.