Woo! Just got my box of these in the mail, time to share.
Set of 1 inch, or about the exact size of a US quarter, heavy duty buttons. Features Bird, Smilodon and Rabbit. Each glows pretty dang brightly after charging under direct light.
They are for sale as a set: [link]
PS: If you want to order more than one set at once, please contact me first, the site doubles up the shipping cost if you buy more than one item, and I'd rather just charge for a flat rate.