Pony jars, 3 for $1.00 (plus s/h, and tax if you live in my state :) They are approx 2-1/2" in diameter, and almost 1" tall. They are not on our web page at this time. Must buy in increments of three. Email me to order.
I would bet these are the exact same thing as in a popular stamp company who does home parties catalog; I buy mine from directly from the manufacturer of the pony jars.
Here are a couple pix of them so you can see what they are. We have sold thousands of these at stamp shows over the years.