Many brand-named plastics (Plexiglass, Altuglass etc) belong to Saint Gobain.
Here's a list of per-country subsidiaries:
http://www.saint-gobain.com/en/html/societes/f_pays.asp
try "western europe"->"norway"
there are a few companies selling St Gobain products, and there are chances they carry products from other manufacturers.
Tubes and rods may be hard to find though, good luck.
(edit) St Gobain own the Tygon brand BTW - so there are good chances those resellers carry Tygon (at Euro prices, as you'll see)