I was given a completed set of these Man, Myth and Magic encyclopedias a while back for free from a family member who just didn't want them anymore and wanted to clear out space from their home.
I decided to try it out on Ebay and also promoted the listing on Ebay to advertise, although that came along with more hefty fees of course, but I felt it was worth it just to try to get it sold.
Someone offered me $200 against my initial listing price of $225 and I accepted but then Ebay took about $45 in fees and my cost to ship via UPS was was about $35 because the box weighed nearly $40 pounds.
All things consider I lost a lot of profit potential in fees and shipping, 40% of the total sale, but since this was a free item to me it's still money in my pocket to pay for my new Pokemon side venture.