i have 2 15" under each of my seats, one on the celing, one 6" in my homemade dash bord swich box, under bodies and 4 LEDs in the front of the car.
most of which are hard wired to my cigar lighter (u know that lil plug in the back) then to swiches from there
the under bodies are wired to a fuse in the engin compartment
i got all of them at autozone, exept for the under bodie kit i got it at advance auto-parts for