You would never provision such backhaul anyway, it would only be 1Gbps tops which would possibly set an RSP back maybe $2-$3k per month to get it back to their POP. That's excluding any hardware costs or any data cap. That's why small scale solutions can't work unless people are willing to pay more for their broadband.
You could easily run 100 users off a 100Mbps backhaul providing you aren't going to offer unlimited plans because the few that choose to exploit it would run it for the other 98 users.
Chorus upgrading their equipment and moving to Ethernet based backhaul could still be in the vicinity of $100k - $150k