In article , gray bale
writes
I've thought about constructing my own, but have reservations.

Has anyone actually built one, and could share there experiences.

Yes, we built our own poly-tunnel about 10 years ago - very economically
and very successfully. It is approx 30' x 16' floor size.
A friend who had not been able to cope with the differences between
tunnel growing and greenhouse management gave us six hoops; we set those
at 6f.t spaces into two rows of sleepers 16ft. apart; we bought a
standard UVI PVC cover for it, the only cash expense; I built barn style
double doors for it both ends and erected a staging all along one side.

Now ten years and three new covers later we bless the day we took the
project on. We grow anything and everything in it. It is an ideal
supplement to our two greenhouses and conservatory, it stands in as an
extra potting up shed, and it gives me garden tool storage and Joan a
summertime place to keep her ever growing stock of spring bulbs - etc.
etc. We shall renew the cover again next Feb./March, they last 3-4 years
on average. I have considered getting a second one sometime.

Go for it, but just don't try to put a cover over it on a windy day!
--
Alan & Joan Gould - North Lincs.