If you're looking to buy Shatter, you're probably going to have to go online. I finally broke down and bought the Serena Williams Simply Smashing! set, which includes the Shatter polish and a cool chartreuse green (I wear this color a lot). I bought the set off Amazon, and with shipping it came to around $15 and change, which ain't bad. Amazon had the Shatter polish by itself for as low as $4.50, but when you add almost $5 in shipping, you're pretty much paying full price. However, for the time being, this looks like the only option for buying Shatter.
Note: If you purchase this polish off Amazon, be sure to know that you're not actually buying the product from Amazon, but from an individual who sells on Amazon. Most are great sellers, but there are a few bad apples. Make sure your seller has at least a 95% approval or above.