I have usually bought them from Summit, unless there is something special, and I try to make either very small packages or "very big", to make the freight reasonable.
There is no reason to pay much in shipping for just small stuff. Then it gets more expensive instead He..He..
Sometimes I use my dad, since he often orders from Lane Automotive/Motor State, then I just add some parts to his orders.
They seem like a nice Company, especially if you are into more racing stuff.
I am not though, so regular shops have most of my needs.