Though I prefer the asthetics of wood to metal pipe, in many parts of the country you can purchase used oil field tubing. 2 7/8" pipe is a good size. It comes in lengths of 29'-33'. Sometimes it is difficult to weld due to magnetism in the pipe, so you have to coil one of your welding leads around the pipe several times to nullify it so the arc will stabilize when welding.
I helped build a pavilion with oil field tubing. We purchased steel plates with rebar welded to the bottom and set them in position in the slab. After the concrete cured, I welded the post upright on top of the plates.
I also welded 770' of fencing made from 2 3/8' oil field tubing.
If you weld, you can build a simple pole trailer for carrying pipe, or you can cut it to length before transporting.
Call the numbers for your
local scrap haulers in your area advertising in the paper and tell them you will give them cash for whatever size pipe you are looking for. You will probably be surprised with how quickly they come up with it, and the price should be reasonable. Figure out the weight per foot of what you are looking for and give them .15-.20 per pound for it. They only get .04-.10 per pound for it when they
sell, but if you go to the same recycle
yard to buy you will pay .40-.50 per pound.