My school was recycling old Lenovo desktops that worked perfectly. I was able to get one, added a GPU which then required a better power supply so I added that too, last thing I changed was adding an SSD instead of the hard drive that it had.
Because of the age of the computer and it being a Lenovo desktop some of the hardware isn't in the list so I made my own list for the older components.
*edit Added a wrap to the pc shown in the last picture.
CPU Intel I5 660 Ram 4x2gb MotherBoard LENOVO Part #: 71Y5975