Like others, I use Momento inks. I also like digi stamps, so I use my ink jet printer to print images. I was at Hobby Lobby a few weeks ago and found special paper for Copic markers in the art section. It came bound in a notebook. It's a little thinner than Card stock, but I get fantastic results and the price was very reasonable. I made this card
using the paper.
Sorry, I don't have a conversion chart, but I would love to have one too.