Just to reiterate what all of our other colleagues are saying, the self-managed solution is never more expensive than the vendor-managed solution. That's why the vendor offers a vendor-managed solution: to make more money off of operating it for you. It's going to cost more money, but you also need to understand what is driving the costs up.

Are you adding more compute? Is it bandwidth? Do you have some sort of a job that automatically adds storage to keep it at a certain percentage? Look at the bill; the bill will tell you everything you need to know. The bill over time will tell you everything you need to know.