I've found a couple (
http://www.comicbookclassifieds.com/ and
http://www.comicspriceguide.com/default.aspx) that might work, but not sure yet how much of a "craigslist" the first is (where everyone sells and no one buys) or a royal PITA the second is. I was looking to see if anyone had any direct experience with any of these (or others).
I'm sure neither will be like a Net54 as well. *sigh*
I have sold some through
https://www.mycomicshop.com/webuycomics (I believe it's part of Lone Star) about a year or so ago and they paid some fairly reasonable prices for what I sold, which was low-mid level stuff that wasn't in high demand but it allowed them to 'restock". It was worth it to not have to deal with ebay or "the public".
I think there was only a couple books where we had a grade difference of opinion (which worked both ways) so the estimate of what I had was VERY close to what they offered (it might have been slightly higher my way).