Is upgrading to 16GB of DDR3 worth $30?

Yes, if you have 8GB or less. Modern web browsers eat RAM like candy—ten tabs plus a few extensions can easily push past 6GB, causing system slowdowns from disk swapping. $30 for used DDR3 is a no-brainer since it’s reliable enough used and returns are easy. Going from 8 to 16GB will feel like a new machine for everyday use.