40 gallon breeder vertical build

I know several people have done a build like this but what I'd like to know is your opinions on the practicality of it. Why not just get a Exo Terra 36x18x36 or a 24x18x36. I've been thinking about doing a build like this for some time. The only thing I'm not sure about is the door construction.

I'm in cen calif and the Petcos here are starting their dollar a gallon sale tomorrow.