Check out the item on this subject in the Hints and Kinks section of
QST for April of this year.
It is 2 or 3 sections of uni-strut fastened together.
This material is available at Lowes, Home Depot, etc.
It would need to be guyed, but it is a cheap alternative.
I also know people who use large diameter heavy gage PVC pipe.
Mike Duke, K5XU
American Council of Blind Radio Amateurs