You cant moan about someone because they won't sell stuff to you lol. Breaking is a pain in the arse and half the time the money isn't even worth it. I know id ignore someone constantly going on about buying something and not taking the hint when i dont reply.
I used the 12v from the cigarette lighter mate, just make sure you use a good seperate ground. Never had an issue rubbing from a radio live though, previously ran 4 gauges and a manual boost controller off the radio