PrincessDress08 via eBay offers this Mini Round Plastic Plant Pot in several colors for $1.16 with free shipping. (Jewelry Go via eBay has them for a few cents less but they ship in random colors.) That's tied with our mention from a week ago and the lowest price we could find by about a buck. They measure 3" x 2.5".

Note: This item ships from Hong Kong and may take up to eight weeks to arrive.