Where did you purchase materials?
I've happily purchased materials from the Montessori Outlet, Kid Advance, Montessori Services, and Michael Olaf. I'm also no stranger to Craigslist. I can't tell you how many wonderful items I've scored for bargain prices.
Am I trying too hard to make a Montessori school in my home, instead of homeschooling? It really struck me about what you said about not wanting your space to be "overly consuming" or "overdone".
My advice is to keep it simple. Don't feel that you need to have everything out on the shelf at all times. Rotate activities and materials as needed. Do not get down on yourself or your little one, if you notice their interest waning away from the work. He will return. Follow your gut. Follow your heart. Follow your child. Look for signs of joy, contentness, and peace. Listen for the hum of the sweet tune of childhood. When you recognize these precious gifts, you will know that you and your little one are right where you need to be no matter which path you travelled to get there.