Here's some places I've had luck finding U.S. made vice-grips:
1) Any independent hardware store (absolute gold mine, these places)
2) Any True Value hardware
3) Any Ace Hardware
And I know this sounds crazy, but I've had incredible luck at several local Pep Boys stores. Maybe they just don't move stock quickly, but it's a place where you'd never think you'd find vintage tools.
Some tips though. Obviously, if the vice-grip is in an actual box, it's a Petersen vice grip from the 1990's or earlier. If it's in a plastic clamshell, this is not a bad thing, even if it says Irwin on the packaging. After all, Petersen bought Irwin Tools, so it's still the same vice-grips, they're just using the Irwin name to sell them.
Where the problem begins is in 2003. That was when Newell-Rubbermaid bought Petersen (and Irwin). Now, the early Newell-Rubbermaid grips are still the same ones that came before, but you have to look at the date on the back of the packaging and the "Made in" seal on the front. From what I've observed:
1) 2003-2005 - Front of package says "Made in USA". Grips themselves are also stamped "Made in USA" and have smooth surface on bottom of the lock pin.
2) 2005-2007 - Front of package says "Made in USA with Global Components". Grips may or may not be stamped "Made in USA" and there may or may not be a hex key hole on the bottom of the lock pin. My rule of thumb here is that the grips were assembled in the USA, but if the grip isn't stamped "USA" and if it has the hex key hole, then the parts were Chinese but put together in America.
3) 2008-2012 - Front of package says nothing. No stamp on tool, hex key hole on bottom of lock pin. These are Made in China and are what is currently for sale at Sears, Home Depot, Wal-Mart, and Lowes.
All this being said, there is a hardware store near me in Southern California which has an entire rack of Petersen vice-grips from the 1990's (in almost every combination you can think of) and even a brand new Made in England Record Vise. If anyone is interested in these things, I may be able to make a run and get them for you...