Wow,
This is clearly a stunning frame. I can almost feel your trepidation in regards to this and the price. The reason I say this is because I am a craftsman and a builder myself. A frame, just as you see there, could be built and constructed for under $200.
I say this because I am very keen on material finds. I buy "culled" lumber, always, without question. I get such good results from the culled stuff. I put together a 20 x 8 ft garden shed, by myself, all for $500. Probably a bit more for paint though.
Here take a look.
I am always thinking of new building structures based on materials that come my way, but I can equally respond to a frame like that. I can see the simplicity in the construction. A tube bender and the right fasteners and that would be an easy shape to recreate.
Often what I do is sit in the space where I want to construct something. I try to imagine in my mind this structure sitting there in that space. As I begin to see it, I also begin to imagine what it would take to accomplish it; I know this might sound a bit metaphysical in nature, but I sort of manifest the project in my mind, and as it works itself out it somehow manifests itself into the physical reality. Of course with a lot of sweat and tears too! LOL
I cannot tell you the countless times I have tried to incorporate an 'official' greenhouse in my yarden space. I say official because every time I build a structure that begins to become my greenhouse, some critters take it up and their need becomes greater than my own.
So I guess, considering all the benefits and the time to construct (not everyone is as OC as I am), I would say "Go for it".
Why not. It would be the prettiest on the block for sure. I can see some really beautiful things coming out of that structure.
Ron