I was a vendor at a convention this weekend and sold a ton of mug rugs. People were buying them up to 8 at a time. I thought I'd share what I learned. What people bought first/most of were ones that had words on them and funny. A lot of people did not know what they were even though I had posted an explanation and put an explanation into the cellopane packages I put them in. So I started explaining what they were right away when they approached the table and then they got interested. I also gave suggestions about giving them to others as an acknowledgement of a kindess, for birthdays, or when someone else needs cheering up. I packaged them in cellopane bags so that they could be handled and picked up and to keep them from getting dirty. I also put some flat on the table next to the basket that they were in. People couldn't see what's in the basket at first glance, but on the table the mug rugs caught their interest. Hopefully some of these tips help!
http://www.papermart.com/standard-lip-n-tape-self-sealing-bags/id=15038?SearchItemNumber=7585008
I charge $5. Materilas cost me $1.39 to make them. If the design uses a lot of thread, it probably costs me a few cents more. I see on Etsy that some people charge more and then you have to pay postage. This conference was for cancer victims and their mentors. I did not have to pay an entry fee, but donated $$ to support them. If you have an entry fee, you'd have to charge more.
I had limited space, a 6ft table, and was selling other things as well.
http://www.sanfranciscostitchco.com/MinuteMats.html