I wanted to get some spring loaded test probes, but found out these are incredibly expensive... So i tried to design my own (This is my first design done with Autodesk Inventor and my first submit to thingiverse - have mercy).
PTR H 1025 L - precision test tip sleeve (for soldering connection)
PTR 1025/E-BST-1.5N-AU-0.62 - precision test tip
(those two combined should be available for about 2,20 €)
...plus some basic stuff. Cables, Connectors (Banana Plugs or anything else you can think of).
Ohh and: Voltage Rating of those precision test tips is 60VDC. Please don't electrocute yourself!