For steels, cupric metals, and exotic alloys these guys have it.

I haven't had to buy cutters in a long long time - lots of stock and I either grind my own or job special cutters out to a local grind shop (reamers, helical broaches...)

For the indexable cutters (carbide and ceramic inserts) I usually get a list together for such things and order from MSC or ENCO if I can't get them from a local jobber.

McMaster-Carr is a great source!
It's a rare occasion that I don't have my order on the doorstep the next day.
Price isn't Bargain-Basement on anything, but the price is consistent -- and with these guys you're getting the 'Opportunity to Purchase *Today*' !!

Any mild steel sheet/bar/tubing I need for tooling or fixtures typically comes from one of the area's big (industry) metal recycling outfits.

Blain, haven't you ever been to Boeing Surplus?
I used to work across from the Space and Defense Center, right down the road from good ol' "Bo-Mart" as we called it.
We could get anything from tiny carbide drills to full-kit 747 landing gear!

Cheers
Tinker