Just trying to figure out what made SaaS a good value vs hosting on site, were you able to get rid of a server & the associated power & maintenance costs?
Scrappy lean startup who has no resources and no traffic? Great you can bring up our docker container. Growing company? VC backed startup? Large corp? We offload all of your cares for a trivial cost, which is especially important since we're monitoring a core chunk of the 'health' of your business.
On top of that an isolated dedicated VM and database probably cost about $20-30 per month.
To be honest I have not done any in detail breakdown, the main factor was that we did not want to spend engineering resources when we didn't need to.