these are 12 mm with ah 2 mm wall thickness.  each ~24 inches long  so you get 96 inches or 8 feet of glass. Except for the Opaque pink and purple. that is 2 pieces and 48 inches total.
I will combine shipping for you when possible.
The secret to cheaper shipping is buying more than one pound at a time. the biggest break is when you buy 4-6 pounds.  I can pack 6 pounds of rod or 3 sets of 12 mm tubing comfortably in one of my shipping boxes.  What I see on this end is that going from 3lbs to 4 lbs usually adds $1 to $2 to the shipping total depending on where you live. When buying multiples put the items in the ebay shopping cart and ask for a total. This gets the correct shipping total for you.  Thank you for looking.
Gmaw