I've bought end mills from
Kodiak Cutting Tools - USA Made Carbide End Mills, Onlinecarbide
Your Carbide Cutting Tool Source, Shars, and a few random ebay. Onlinecarbide has good prices, and a "basic" selection, made in US. Kodiak has a great selection of end mills as well as drills and taps, but slightly higher prices, made in US. BTW
Kodiak Tooling Solutions Featuring Dorian Tools , a different site has/or had great prices on ER collets.
I've ordered a few times from Shars. The stuff I received was good, but they've always taken a week to ship my stuff, including the "US made only" order that is supposed to ship that day. They are located in Missouri so I figured I would get my stuff quickly, I'm in eastern Nebraska.
Have yet to try Tormach.