We currently use SQL CE databases on the client machines, which then synchronise their data to a central server using the merge replication/RDA functionality of MS SQL. The amounts of data involved is small, and the central server will often be idle for ~95% of the time - it's only active really when data is incoming, and is typically synchronised on a daily/weekly basis.
The SQL Standard licensing costs for this are large, relative to the SQL server workload / the amount of data we're talking about (in the order of 100s of MBs maximum). What I'd like to know is if there's an open source alternative (mySQL or similar) which we could use as the backend data storage for our .NET application. My background is Windows Server Admin, so relatively new to Linux, but happy to give it a go and learn some new skills, as long as it won't be prohibitively difficult. If there are any other alternatives that would be great too.