It's not about getting rid of Microsoft: it's about getting rid of Oracle. Their licensing costs even for a very large shop may start out cheap (think 90% discounts) but will creep up over time. And when you inevitably manage to get a combination of oracle-dependent data, queries, processes, etc entrenched the prices start to climb and the even more expensive options come out. Oh you need more performance? Go horizontal with RAC. You need to go faster but can't reengineer things? Exadata will fix you right up.
While the licensing details can be somewhat complicated, the retail price of ~$7k/core is published on Microsoft's site at https://www.microsoft.com/en-us/sql-server/sql-server-2016-p.... Oracle's pricing is harder to come by but is closer to $25k/core for the Enterprise edition on x86 CPUs. There are often lots of extras involved in Oracle licensing, too, so the total cost differential between the two is generally higher than the per-core license cost differential.
The licensing difference is not that much; what is really different is TCO. Any IT guy can reasonably look after SqlServer, whereas Oracle needs specialised personnel which will inevitably be outsourced offshore, increasing complexity and costs.
And Oracle support contracts (which are basically mandatory) are really expensive.
How hard is looking after postgres compared to SqlServer? I'm a .net developer that's been spoiled by SqlServers ease of use. I just started at a place that use sybase which is a nightmare.
