Pipe towers are a low cost way to go .
But I want to get a way from having  to transport 20 foot section of pipe or do any welding in
the field if I want to go higher.

I have help raise some pipe towers for antennas and if you don't dot your I and cross your Ts thing can get hairy real fast . A pipe tower is 100% dependant on the guy for holding it up and during raising and lowering . A more ridged structure makes life a lot easer. And we are talking
more than just  compression loads.

That's why I am working with 10 foot sections that bolt together.   I can easily transport the materials in my short bed pick up. And the finished 10 foot section weighs in at 41 pounds.

As for cost the conduit cost 14 dollars the angle iron was 5 cents a pound at the scrap yard.
 Now that I am set up I can knock out a 30 or 40 tower'  in a weekend or at most two.
 As I work mostly by my self I want things I can easily handle. I not getting any younger : )