I think Jim and Dave hit it on the head here. I've been in Dave's shop many times and it's a good size, but also very full with tools. I think unless you buy like 5000sqft of warehouse, you're gonna fill that sucker up.
FWIW you can go pretty small. I think I probably build about 1 bow per month on average, but sometimes as much as one a week with downtime in between.
I live in a <1000sqft apartment, all my wood is stored in one closet, and theres quite a bit in there, probably enough bamboo and wood for 50bows; but it's very organized and I constantly revisit it to clean up. Most if not all of my work is done on my porch which is maybe 6'x14' with a bench that is 2'deep, so maybe only 6' x 14' of usable space. It's workable but as Dave hinted at, the less space, the less efficient your work process.
Whereas Dave can build an entire piece of furniture without any serious clean up, I have to thoroughly clean after every major wood removal on something as small as a bow.
Here's the basic equation: As space goes down, planning and preparation must go up, and efficiency WILL go down.
My most adventurous build was an 8' wide 44" beam sailing dinghy which I designed and built entirely from scratch including hollow wooden mast and all rigging with no power tools other than a hand drill on my 6' x 14' porch. But you better bet it took twice as long, and planning was twice as critical as it would have been in a 2 car garage; but it's possible.
So long story short, use what ya got cause it'll never be enough anyway.