Try looking locally also in your yellow pages of your telephone book.You will be limited with styrene tubing,Plastistruct is the only company that sells it to my knowledge,and the diameters are small,as are the lenghts.They do have a variety of plastic shapes available..it's been a while since I've visited their web page.Acrylic tubing is different,any serious plastics supply house will have extruded&cast lengths of acrylic tubing&rod(also square stock)posibly other shapes,and mostly in 6ft. lenghts.
how to get styrene?? - this is what I did. I looked for a plant/site/production were they made lightsigns, billboards, vaccumed stuff, assorted commercials on cars etc. and found a local facilty.
They usually have a lot in stock in there warehouse, so I got alot of it for a 6-pack.
So I have a lot of it now, in assorted thickness for almost nothing. This will keep me going for a long time.
Evergreen is another company that makes shapes, tubes and rods. It is available at your local hobby shop but is expensive! Wow Moe, I never thought of that. I have 3 local sign co.'s that maybe ripe for the picking!!