I have a 13" MBP 2011 with a 128 GB SSD but I'm starting to run low on space, and I don't want to keep plugging in external HDD to put stuff on every night. Have any of you guys swapped out the superdrive for an HDD (probably SSD?), particularly this exact model? I read somewhere that you must purchase a holder for the drive, which is quite expensive. Any DIY alternatives for cheap asses like me?