NexusDB

No, it is not. Please take a look at MySQL Licensing.

In a nutshell it says: If you don't release the source for your application under the GPL you need to acquire a commercial license for mySQL. A look at the pricing for commercial mySQL license:

MySQL Store.

The MySQL Server license is per database server per year. There are no restrictions on the number of connections, number of CPUs, memory or disks to that one database server so these are per deployment royalties.

Price per server per year: £1,344.00 - about 2050 AUD.

NexusDB at AUD 750 per Developer costs less than half of than MySQL or in other words:

MySQL is significantly more expensive than NexusDB and NexusDB thus has clearly the better price value.

This doesn't even take into account the costs for support and whatever component you plan to use to access the mySQL Server (which is normally licensed per Developer as well), the fact that you get the full source code which also contains a ton of other useful stuff.