One thing everyone should add to their list is a 25 and 50 gram weight. There are dozens on-line for dirt cheap, and it it gives you the confidence that your inexpensive weight scale is accurate. Several times I have used a picture of the 50gm weight, and then the weight of the coin to some in a distant country to give them the confidence that the coin actually weighed what I said it would.
Also, look for 1 with a lid, and operates with batteries that you can easily replace. The 2032 batteries are expensive to replace every couple of months. I like the one posted that runs on AAA batteries, available everywhere.