For sale is a second hand Seagate Momentus Thin 500GB SATA drive.
I have tested it an it is in working condition (See the screenshot from Seagate Seatools
Part number: 1DG142-020
Serial number: W3POSGNV
Date of Manufacture: 10/2013
Drive is located in Hamilton, but am happy to post at buyers expense.
Similar drives look to be going for $45 upwards on Trademe, so think $30 is fair, but am open to near offers though.