i have been looking into building a skimmer lately and have priced out some 6" acrylic tubing all 1/8" and if you buy a 6' length from industrial paints and plasitcs in Calgary they will sell it to you for 105$ nearly halfs your main chamber costs.
they are located in the industrial park in the s.e. near chinook center, they also had the 6" in stock when i was there last wednesday. also i found a site on the internet
www.k-mac-plastics.com they aslo sell the acrylic tube for less then you say you can get it IF you buy in a 6' lengths. hope this helps you some.
Richard