I agree mostly with what Twisted has to say...but
I have a few points worth considering/ranting about. I'd like to say first that I agree buying should be in a person's head when purchasing products. Supporting the economy is definitely at this level should be somewhat important to Americans. I'm not American (I'm Canadian) but have been living here for ~6 years and I try do buy American as much as possible on my lowly student budget. I realize supporting the economy that I live under is important and frankly there are a lot of great US made products.
Onto my points, firstly, buying imports is not killing the American economy, imports have been around forever in this country. This administration is killing the economy (that was a major pot stirring statement). I have no vested interest in politics since I am unable to participate in elections here, but I have followed along since I have lived here and it is pretty obvious that the current ecomomic problems are mainly due to the current administration. You just have to rewind a few years to the Clinton administration to see this fact.
Secondly, I agree with wm69's sentiment that (and this is a gross generalization of course) pride in American workmanship has fallen dramatically. I think that unions may be a signifacant factor here (another major pot stirring statement, and yes I have been unionized). Unions were a great idea and essential during the first 3/4 of the last century, but recently things are getting out of control. People want more money, more benefits and want to do less work. It's a terrible attitude and unions promote this. Why as an American business owner/manufacturer would I pay an American employee X dollars (+benefits, etc.) to do a half assed job when I can go to another country and pay a worker there X/2 or X/3 dollars to do a better job because they are overjoyed to get work. And this doesn't mean that it will be a sweatshop, since standards of living are much different in other countries. The same thing is happening in Canada now, US companies that once built factories in Canada for cheaper (certainly not sweatshop) labor are bailing out to go to Mexico and other countries because Canadian workers want more to do less. For example, Twisted's example of Levi Strauss, now Hecho in Mexico, used to be Hecho'd in Canada long before moving to Mexico. I know I used to work one of the 5 Levi's plants in Canada (unionized). Now all of these plants will be closed as of the end of this month.
Work attitudes are also reflected in immigrants to this country who work their asses off doint the jobs that US workers refuse/don't want to do (like taxi drivers, custodians, dishwashers, ect. etc. etc.). At some point people should be made to suck it up, get off their buts and work for a living (and of course this is a gross generalization again because this attitude is held by only a fraction of the population). Hell my mother has been in the service industry for 25 years, managing various restaurants over that time. These days she can barely keep dishwashers staffed because kids these days just don't want to work (gross generalization), and if they do they want this day off and that holiday, etc.
Anyhow, I'll stop ranting here and leave you with - Yes, buy American when possible but don't screw yourself on quality or price and it's time for pride in American (and Canadian) quality and work ethic to improve. You can't have your cake and eat it too!
P.S. One of my favorite things here is in the maple syrup lane in the grocery store. Title on the bottle - "Pure Vermont Maple Syrup" (in small letters below, product of Canada). LOL