Want a greenhouse without spending a lot?

In recent years I have developed the desire for a greenhouse.  This has come about for a few reasons.  Mainly, I don't like all the leaves that fall off my ferns when indoors!  Then there is the space issue and a bad case of spring fever which usually hits late January or  mid February.  Not totally sure what all I would use the greenhouse for, I didn't want to spend a lot of money on one.  After a little thought, it hit me I could convert my arch garden into a greenhouse for the winter.  In the winter the arch garden sits there as waste land.  In the summer, I really have no need for a greenhouse.    Also, having a greenhouse around the arch garden would allow me to get the archway plants started a little earlier.  Sounds like a win/win.  At least for the moment.

I will save the details on how I built this for another day.  Mainly because I want to see how well it holds up first.  Most of you get the gist just by looking at the picture.  In short, the arch garden is made with cattle panels and t-post.  Basically just added plastic and duct tape to enclose it.  If you decide to try this, or have a plan of your own, I would love to see pictures and hear about what worked, or didn't work, for you.
Cheers and God Bless!