Oh!! THAT size would be fine for 20 I think. I thought you meant 8x12 total footprint like the one I have.Is 1600.00 with a 144 sq ft run and 8 x12 coop too much ,it has a lifetime warranty .
I don't guess that price sounds too bad, but it makes me cringe because my hubby would build it far cheaper for me.

I am familiar with the guy you speak of though, and his work looks very nice. And with a warranty, makes it even better. :shrug