From a book called Access 2013: The Missing Manual:
At this point, you're probably wondering how much that part in the center of Figure 21-1—the SQL Server database engine—actually costs. Microsoft sets the price using a complex licensing scheme that ratchets up the cost depending on how many people use the database at once. Usually, it runs into thousands of dollars, and it's not uncommon for a big business to shell out $20,000 or more.
But before you skip this chapter in disgust, there's something you should know: A completely free version of SQL Server is out there waiting for you. Amazingly enough, it's almost as powerful as the one that costs thousands of dollars and requires you to pledge your first-born child to Microsoft.
Honestly, I have no idea what that's supposed to mean. Any thoughts?