I've got a few lots and several individual pieces of Polka Dot Agate listed on e-bay. There is a good assortment with lots of variety. Good old stock material. I am told it has been sitting in the sun for 20 years so any color is stable. Lots of good scenic pieces. Most of the listings are BIN, and price is negotiable.
Here is the link:
http://www.ebay.com/usr/jgb1224