this may seem crazy but I’ve bought and sold audio engineering equipment where you want to show it works and I’ve brought something like the link below to power it - this 100% can support most stuff outside a 700W PC w/ GPU, just a suggestion...
For the computer/electronics stuff, selling it here (or similar places like TPU, MacRumors etc) is your best bet....not saying you absolutely can't get scammed, but the chances are way, way less than those other places you mentioned.....I've been...