Cost savings - other choices
Whilst I heartily recommend mySQL, I strongly advise anyone choosing a new database to consider PostgreSQL. I personally found mySQL underspecified; its particularly clumsy at the current version in handling triggers. We ported directly from Oracle 9.x and found the transition to Postgres quite easy; the prediction for mySQL was far more difficult and inelegant/more difficult to maintain. We have found Postgres approximately as stable over the last year as Oracle was in the prior year and have saved approximately £10k in annual Oracle fees.
Note; I have no affiliation with any company or developer or toolset.