1. You probably don't need SQL Enterprise
The most significant money-saving opportunity for Microsoft SQL Server is downgrading the edition of the server from Enterprise to Standard or even Express. Check edition features, and make sure you look at the actual version you are running, as feature sets may differ in different versions.
2. SQL Server Express is free of charge
It is vastly underestimated. Microsoft has been adding previously expensive features to less costly editions with almost every new release of SQL Server. So maybe you don't need SQL Standard to run some of your workloads.
3. Classic clusters
SQL server dramatically benefits from the consolidation of instances. And that is a massive advantage for hardware clusters where on a powerful piece of hardware, you may deploy as many instances as you want under just one license. Note: I do not mean virtualised clusters. I am talking about hardware clusters: multiple nodes, only physical operating systems, multiple SQL Server instances, clustered.
4. Passive instances
Passive instances don't always require licenses. Since SQL Server 2012, SQL failover requires active Software Assurance, but if you already have Software Assurance on your licenses, why don't you deploy passive instances for free? And recently, Microsoft has permitted deploying additional passive instances in Azure.
5. SQL Server Developer
SQL Server Developer is a free product. It is an equivalent of SQL Server Enterprise for development, test, demonstration and design.
6. Dedicated clusters
You may also benefit from consolidating SQL Servers on dedicated clusters in the virtualised world. You can license every processor core at the hardware level with SQL Server Enterprise and get unlimited virtualisation.
Would you like to know more? Please don't hesitate to send us a message, and we'll look into that together.