Assume it was 1-click and 100% automated to deploy, run and update a Hub.

How much per month would you be willing to pay to run one? 

No direct economic incentive other than you know you're supporting Farcaster decentralization and you have your own copy of the network.

OK, if you're answer is you wouldn't run one.

Working on Farcaster and Warpcast. Longer thoughts at https://dwr.email

$10/month max.

That will require me to be very active on the network for it to go beyond 6 months.

There should be a path for shared hubs, where small clusters of users share/rely on one hub and that way cost can be amortized.