Building is definetally more expensive than buying. I also use all-glass aquariums as a cage for my corn. I was planning on building a cage with 2 sections. One for my corn and one for my new one. then a stand that would serve as a baby rack. Well i'm not building the cages anymore but going ahead with the baby rack. I can get birch plywood (3/4") for $20 a sheet. Good luck!
John