Great idea - wrong platform. Cisco specific solutions
aren't reachable for many.
Look at Linux (Raspberry Pi) solutions or powerful,
affordable routers like MIkroTik and common tunneling protocols
like OpenVPN, L2TP, GRE, etc.
The big advantage of Cisco DMVPN is that it can create a fully
meshed tunnel network with endpoints
on dynamic addresses, with only one (or a few) central hubs on
static addresses, fully automatically.
It is like what you have with a JNOS or Linux route importing
encap.txt all the time, but without the hassle.
Other VPN solutions are usually hub-and-spoke, where all internode
traffic goes through the central hub.
It is like connecting to net-44 by tunneling everything to
169.228.66.251 instead of loading a routing table.
Rob