Nathan,
Maybe your local steel service center has 2X2 cold rolled steel. Ask them for a "drop" and see if they have anything in the length that you need. 2inch sq. "key stock" from MSC is listed at $43 for 12 inch piece....ouch! You can beat the heck out of that price with 1018 CRS. Look in your yellow pages for "steel" ...service centers and see give 'em a call. Besides if you don't get it local, you'll pay a mint for the frieght. That piece will weigh about 15.8 lbs. I would expect you to pay about 12-13 bucks if they don't charge a cut fee. That's why you ask for a "drop" (scrap).
Take care,
-Rob