Apple iMac 27" Late 2013 i7 3.5GHz - 16GB - 512GB SSD - GTX 780M 4GB | eBay
maxupgrades.com: Single SSD Drives kit for iMac 27 inch 2012 Models with SATA Blade SSD Module / Heatsink/ Power Cable and DATA Cables for [SSD + HDD] with iMac Adhesive LCD Tape
Hard Lesson Learned With Late-2013 Apple Products Containing Lesser Performing 128GB SSDs | The SSD Review