I've never used them. Just went to the site.... $6 shipping for up to a $15 purchase and $7 for up to $40?
That is a HUGE cost. I guess if you're ordering over $100 of supplies, it's ok, but it isn't the place to be shopping for a few 2x2's.
As far as I'm concerned supplies are supplies. When I'm ordering coins from somewhere, I always see if I can't piggy-back some supplies on to the order for essentially free shipping.