As a HAM I two bought telescoping fiberglass poles 10 years ago from this vendor -
https://mgs4u.com/fiberglass-push-up-masts/#mastsI bought their heaviest mast and a lighter one, because the cost to ship two was about the same to ship one.
I used three of the lower sections for the configuration pictured, though not from the heaviest duty mast. If you're going to buy one I recommend the heaviest 50 footer.
I don't remember what I paid but today the heaviest duty mast would cost $426.59 delivered to NY, this includes 8% tax.
I have taken the whole kit and kaboodle down and put it back up, it is a one man job.
Steve
p.s. these poles are made to give and the wind load of the anemometer will not tax to poles too much. There hasn't been winds over 9MPH since it's been up and the "sway" has been nothing.
pp.s. The bottom pole of the heaviest mast will absolutely not fit into the Davis ISS U-bolt.