Electronic – What options are there for good Low DC Voltage, High Amperage Alligator Clip connections

Forget category c: some things are truly disposable and can't be reused in their current state unless you want to start a recycling company.

Category B is the most interesting. For tools, there's eBay: just resell stuff you don't need. Even then, a lot of what we do is specialty stuff: I have 6805J programmers that no one wants even for the cost of shipping. They've simply outlasted their usefulness.

The problem with reusing hardware is the documentation has to be perfect, or the time spent trying to reuse a board or other hardware becomes more costly than simply starting from scratch again. I find that for the things I build for other people, I'm pretty good at keeping good documents. But for stuff I build intending to use for few days and then forget about, documentation is pretty much none existent, so boards end up permanently consigned to the junk bin.

In my experience RCA plugs make a very tight connection, and I expect the resistance to be way less than 50 mΩ, probably near 10 mΩ. Even at 2 times 50 mΩ (you have to count both pin and sleeve) a 500 mA current will cause a 25 mW dissipation, which is more than acceptable.

Matt makes a valid point about mixing them up with audio plugs, though. The wall-wart probably has a DC jack like this

Why not use a socket for that? These are almost exclusively used for power supplies, so there's little chance of confusing them for something else. Sockets for them are readily available.