Watch the Group Buy section, last I cehcked SPMotorsports had them too.
I got mine at Lane Automotive @ SZ 02. Expect to pay about $160-170 if you can find them in a GB or close to $230 if you go through SP. Slim might know of a better place as I think he is usually responsible for setitng up the GBs when they happen.
I know his How-to rocks! It may look like nonsense until you actually have the brackets out and in front of you, but once you do, its smooth as silk!