Are you selling to make quick cash? If you are selling them to just clean up the clutter, and make some spare change, I'd suggest eBay. Start small selling individual issues/one offs, until you have a good reputation. Then start selling items there in bulk.
My bro sells a lot of photography equipment on eBay. He makes good money selling to people in small towns that do not have camera stores. The same towns that don't have good camera stores don't have good comic shops either.
Have a reasonable start bid the least that you will part with the comics, and have a Buy Now price that would be $.50 to $1 less than appraised value. Figure your time and materials into the shipping and list it up front.
I hope you get most of your cash back.