Previous (closed) thread on the subject:
2x1x1/16th Aluminum Extrusion Availability (East Coast)
Here's an east-coast source for 2" x 1" rectangular tube, .065" wall, 6061 aluminum.
D & M Metal and Industrial Sales
527 J. Clyde Morris Blvd. Unit C
Newport News, VA 23601
dmmetals@machine.hrcoxmail.com
office: 757-594-8052
fax: 757-594-8053
At the time of writing, it's only available in 61" lengths. D&M's upstream supplier currently has 25 pieces at 61" LG but can get more.