Simple laws of physics and the flow of electricity, if you touch the METAL case to discharge your static buildup it is impossible to transfer any electrostatic charge onto another component.
I bought one of those a long time ago from the only local store I could find that had it, then once I opened it up I realized the cable was way too short to make building computers with it on possible.
Do you have any recommendations for a place that sells long ones?
I don't even touch the back of a plugged in PSU now. Hugely over rated. I build vomputers of thick carpets, with socks on and don't do anything to protect the components. Spend that $10 towards something useful.
Don't wear socks, work on a wood surface, and work on a non-carpet surface and you'll be fine.
Make sure you hold on to a metal part of the case frequently, so that if you discharge any static it will go to the case and not static-sensitive parts.