I got an off-warranty Dell Precision from a previous employer. They were cheap and ordere them with the lowest Xeon CPU at the time, so I spent $100 on RAM/CPU to max it out. 6 sticks of 4GB DDR3 and whatever the Xeon equivalant to the i7-950 was, and threw a couple leftover 2TB HD's in there.

Made a great server. But for a workstation it wasn't really that snappy and I just ended up using a 2016 MacBook Pro.