What you've described sounds a lot like running an AS with BGP. Yes, there's centralized allocation of ASNs and IP ranges. Otherwise, the whole thing is pretty decentralized, but you've got to figure out how to connect to peers and transit providers.
Many peers will connect without a real contract, especially if you're both present on a peering fabric, but transit usually needs a contract because transit isn't mutually beneficial.
For some sort of overlay/alternative network, reliable transit seems highly likely to have a cost too. Probably not a contracted cost while it's experimental; and maybe optimistically, much lower than today's costs for IP transit, but still there would be a cost. Actually, IP transit costs are much lower today than years ago, but last mile transport costs are more important to your bill and running wires requires skilled labor and specific capital equipment, so it remains expensive; bandwidth capacity of wiring increases over time, but you still need one connection per home for best service; although wireless seems poised to reduce costs for good enough service in favorable conditions.