As Geezer mentioned a great place to look for Cotis is in antique stores and also flea markets. I found a natural combo Coti for a buck at my local flea market. I have a store bought Coti as well and would say my pedigree free stone is just as good. This is a cheaper option to enter the game, but on the other hand it may take more time. What are you currently finishing on? I must admit, I too had the Coti fever and bought the initial stone, but now I would never pay full price again. That's not to say they aren't great stones, but they are very popular and have always been popular. That means they are a lot easier to find hidden in antique stores. I may be wrong and this may be the usual mystical, mumbo jumbo of everything old is great, but I have read older quarried Cotis tend to be better stones.