I am thinking around 6-8' long 4' deep and 7' high. Lights would have to be the most economical to run. I want to keep the build and running a budget (I have a wife you know )
How many plants are you considering on growing?
Are the plants already full grown outside or are you starting from seed inside?
How much space are allocating?
Are you growing in pots or some type of hydro setup?