Who do you get your parts from?

I have gotten some parts from Tabco and Mill Supply, I believe Mill's are made by Tabco. However, last time I ordered something from Tabco, it was about two months later and still no parts. Someone called and said one wasn't available at that time and they were just waiting to send both at same time when the other became available. By that time I had gotten a different shell and said to just forget the whole order. I think Mills is better for getting their orders out.