For just a few dollars you can construct a PVC greenhouse like this one.
Building your own cold frame hoop house.
"For just a few dollars you can construct a PVC greenhouse like this one. I've gotten a few questions lately regarding a DIY residential greenhouse made from PVC pipe and greenhouse poly film. Such projects are great way to provide yourself with an inexpensive greenhouse, and
as long as you don't expect a great deal of permanancy out of them, are a great way to supplement your growing season."
I have built 3 versions of a PVC Hoop House over the last 15 years.
They are great for over wintering Tropical bonsai in zone 8b.
The original house is still in use.
New Hoop House 3.0