ElasticSearch is open source and free.
And nothing is stopping you running it on a single node like PostgreSQL. It's also better in every aspect as a search engine.
And nothing is stopping you running it on a single node like PostgreSQL. It's also better in every aspect as a search engine.
If you don't need all the functionality of ES you can go a long way with the Postgres fulltext search. Once you scale enough or if search is your core business ditch it and deploy a better solution like Elastic Search.