Update - I got a bunch of coiled 2" HDPE and was able to get it straight and make some great tubes for just under $0.50 a tube. Ordered 150 plugs from Pyroboom for $70.39 and had all the other supplies needed. Did buy a 2-3/8" Pipe cutter from HD for $24.98. It is a must! Cuts the tubes straight and clean with no burrs or jagged edges. Had the nails already and the finishing gun to shoot then in with.
How I straightened the coiled pipe. I had 4 pieces of 1.5" angle iron laying around and have unlimited amounts of screw hose straps from work. So I connected together enough hose straps to fit around the pipe and the angle iron. Made 3 straps for each piece to be straighten. I placed all 3 on the pipe and iron I was able to put a hose strap about 6" on the end then tightened it to hold it in place. Slide the rest of the straps down forcing the pipe to bend into the grove of the iron. Tightened another strap about the middle of the pipe. Then worked and slid the last strap until I was about 6" from the other end. After that I laid them out where they would get a lot of sun. I was not in a rush so I let each set stay out for a few weeks.
Was able to get straight pipe and nice tubes after all said and done. If you have time on your side and willing to do a little work you can do it.