Check out Rob's post (sorry, I'm going to make you search for it!) on the blue vialed empire combo squares. Not quite at the specs as the staret, but for around 10 bucks at Homey's you can't beat it. Made in USA and within .001 per inch. I tested mine with an engineers square and it was dead on and I'm picky. My larger 16" was only .005 out at full extension and it was less than $20. Just look for the blue vials on the empires.
I think you'll be happy with them. (they're not the double square, but...)
That's not even a smile! That's just a bunch of teeth playing with my mind!