Hi everyone, great information in here, thanks so much for posting. I'm in a similar spot, too many slabs that I had the intention of selling but no time.
I'm also from Canada and was thinking of using MCS for consignments, so it was really helpful to find this. @thehumantorch question for you -- who do you use to ship and do you have to pay customs to get your comics down to MyComicShop? I've looked through shipping options and customs and the cost seems really high. For example I have about 30-35 slabs to send down, bought a big box, and was quoted $400 to ship. I didn't ship it and am looking for other options now.