I have a similar idea and your pricing is on track. Most people seem to price according to cost and think they're clever charing $9/mo. for hosting.
The technical side is not particularly difficult aside from dealing syncing and maybe failover. What is trickier is probably the CMS side because building a CMS is like the definition of feature creep. Eventually people want/get every feature under the sun, even if that doesn't really scale.
You probably have an interesting business there, but managing customer expectations and finding the happy balance in terms of investment is tricky.
Also, the customer acquisition side of the business is somewhat tough, but worth solving.
The technical side is not particularly difficult aside from dealing syncing and maybe failover. What is trickier is probably the CMS side because building a CMS is like the definition of feature creep. Eventually people want/get every feature under the sun, even if that doesn't really scale.
You probably have an interesting business there, but managing customer expectations and finding the happy balance in terms of investment is tricky.
Also, the customer acquisition side of the business is somewhat tough, but worth solving.
Good luck!