I had mine delivered as a portable garage. You can see it here at the back of my lot.
I prepared a stone pad to place it on then it was delivered as a unit.
But I do know they offer garage plans for larger garages. They usually build in just a few days as it is a partially prefabricated...
I tried growing with lights in my garage turned office space, but had little success. I was growing with an aeroponic system and was just not able to get things going well. Then there was a problem with bugs. I finally gave it up and decided there is nothing like the real light that God provides!
I do have a garage from Sheds Unlimited and really like it. The only regret I have is that I did not buy a larger one.
Advice: Go bigger than you thought you needed!