ebay has them as well as oemtakeoff.com has them also. I actually just bought a gt500 shift boot and a stock shift knob for my '06 off ebay on Monday night for $35 total to cover up my Hurst shift handle and to replace the shift ball. I actually kind of like the stock shifter look on the S197's.
There's a 6 speed one for your car. I know a lot of people don't like ebay, but I run the ebay store at my work and know there are a ton of other people who are respectable on ebay like me lol
There's another one. The first one says its for a 2005-2008 which is random, but it's obviously a 6 speed. The 2nd one seems like the person doing it knows it's for a 2011-2013 lol.