When having satellite radio installed, where does the power supply come from? Cigar lighter or elsewhere?

I read that if you install an aftermarket Sirius or XM radio yourself, it says you plug it into the cigarette lighter. Problem is, I don't want to plug it in there seeing as how I only have one. When I get it installed at Best Buy, PC Richards, etc. do they install the power supply elsewhere, i.e. the ignition switch?