I applaud your commitment to buy American. Maybe it's hopeless any more, but we have to try.

Like Tubtar said, you can find some nice collections of tools from retirments on CL. With machinist tools, I always figured I'd rather have top quality american tools that were used and well cared for than cheap, new tools.

In addition to some of the tools mentioned, I would for sure get a 0-1 micrometer, (get all your mic's and dial bore guages graduated to .0001), get a 1"- dial bore guage for checking lifter bores, get a 6"and a 12" dial caliper. (12" for checking deck height when you are anylizing a used block)
I really like the Flexibar 505-1851 flexible dial indicator stand at Enco, it is so handy and easy to set up compared to a stiff arm.

Most of my tools are 10 - 40+ years old, so I don't know what the new stuff is like, but the brands I like are Browne and Sharpe, Starret, Fowler.
Good luck, have fun shopping!