Around here in the northeast US the almost universal aluminum canoe pole is 12 feet long made from a high temper corrosion resisting tube (this usually means something like drawn 6061-T6.) with an outside diameter (OD) of 1.125" and wall thickness of 0.058" Drawn tubing usually has better dimensional control and (depending on where you look) better mechanical properties.
For this project, the basic materials were 6063-T832 drawn aluminum tubing, available (in UPSable lengths of 6 feet) from Texas Towers http://www.texastowers.com/aluminum.htm). In May of 2005, they were charging $1.35 a foot for the 1.125"OD stuff, and you'll be hard pressed to do better at your local metal store, even if they do let you in off the street.
Material note: 6063 is usually referred to as an "architectural grade" - code I think for appearance being more important than mechanical properties, but at T832, the properties of 6063 (hardness, strength, ductility, etc) are so close to those of 6061-T6 (a "proper" structural grade) that the differences are practically meaningless.
The 1.125" OD x 0.058" wall tube gives a nominal 1.009" inside diameter, so a short inner sleeve of 1.0"OD x 0.058"wall tubing is usually used at the joint.
The length of the inner section is up to you. I used 12". I dunno whether Texas Towers will sell you just a foot of it.