Treehouses

I wonder how much money I could make if I started a side business of building custom playhouses/treehouses for people. Surely wealthier individuals would fork over some buckets of cash for a sweet kid casa. I am almost done building my daughter's treehouse, which is made almost entirely from old repurposed wood. Most of it came from my garden planter boxes. On a side note, for any one who cares, the garden was an approximately 70% failure - part too blazing hot - part weeds got ahead of me. Back to the treehouse, I only spent about 30 bucks and it will be complete in the next day or two as I am just adding the final details.