For Domestic shipping I think you are right, but I haven't looked at it in a while.
International shipping has limits, some, I think, are as little as 5 or 6 lbs.
I do know that about 20 lbs. worth of Slot Tokens got shipped OK in a small flat rate box for the $5.25, (had a lot of tape on it to make it strong enough) not a bad deal!