To anyone who's interested:
Oracle Spatial is now free (as of December 5, 2019).
Oracle Advanced Analytics and Oracle Spatial and Graph Licensing Change
Effective December 5, 2019, Oracle Advanced Analytics (OAA) and Oracle Spatial and Graph (OSG) options are included with Oracle Database. This affects Enterprise Edition, SE2 and Database Cloud Service (DBCS) Standard Edition and Enterprise Edition.
This licensing change encourages and enables more customers and prospects to use the full breadth of Oracle Database. Technologies like machine learning, graph analytics, and spatial intelligence should be part of almost every modern application, and Oracle believes that these technologies should be broadly available to all Oracle customers.
While these capabilities are widely used today, the added cost of the database options have prohibited adoption for some customers. The removal of cost as a factor, combined with recent additions of developer and data scientist-friendly Oracle Machine Learning Notebooks and self-service tools like Spatial Studio with Oracle Autonomous Database, offers a more all-inclusive data platform for developer and data scientist communities.
That's a big deal for organizations like ours. We currently use the St_Geometry spatial type, but St_Geometry has some significant limitations like the lack of a GetVertices function and the lack of linear referencing functionality. Moving to SDO_Geometry / Oracle Spatial would solve those issues.
Hopefully that's helpful to some people. Oracle didn't seem to advertise that change -- so a lot of people didn't know about it (including us, at first).