Try Production Tool .
Several years back I bought several boxes of square head bolts and nuts. They didn't have them cataloged at the time but my sales person ordered them for me. I had to take full boxes because they wouldn't stock them at the time anyway. I still have some of the smaller bolts but the larger bolts had fewer in a box and I didn't get a lot more than I needed for what I was doing.
They were a little more expensive but not all that much or I wouldn't have popped for them.