I try to purchase local as much as possible, even if it's more expensive (especially locally grown produce). There is a general breaking point, though, where I'll shop somewhere cheaper if the price difference is drastic.
There are things that I cannot get local, though (bananas, oranges, etc) and I'll have no choice but to buy them "non-local", but I try to get US grown products where possible. It's not out of some bullshit sense of nationalism, it's more about keeping the locals employed.