Just like the title asks, Where can I get a metal strip in the US? I am modifying my 10 frame langstroth hives and I need a metal strip. I’m just curious what others in the US are using and where they got it. Thanks
I didn’t have time to search their whole catalog, but these guys have a lot of strips in various materials:
http://www.hobbylinc.com/htm/k+s/k+s9733.htm
If I was doing it, I am lucky, I have a small marine hardware fabricator nearby, I think he would cut me a metal strip to my specs for a pretty low cost. If you don’t have marine fabricators, you might try a repair shop at your local small airport - they often have custom metal workers who cut metal for repairing aircraft, and you might even get an off cut free if they like you! 
If you are willing to go with aluminum, you could also consider this:
http://www.homedepot.com/p/Crown-Bolt-3-4-in-x-48-in-Aluminum-Flat-Bar-with-1-8-in-Thick-44650/100337842
Lots of good deals on eBay and Amazon. Just search for “[aluminum, titanium, steel, brass, etc] flat stock 1/8” (select the metal of your choice).
Hobby shops or home improvement will carry steel and aluminum stock in various shapes sizes and widths. Check with the smaller guys like Ace or True Value, they typically have more of the specialty or hard to find things. Worst case look for door thresholds