LED emergency lights

i am a fire fighter were i live and im looking to retro fit my pickup truck with some flashing led emergency lights unfortunately money is a bit tight so buying some from a catalog is out of the question....... i was wondering if it would be cheaper to build my own and if so wat would be the best way to go about doing so?

I saw some drivers for sale on the international outdoor site that are made for flash between the different colors and whatnot. I think they were in the $5 range for the driver that controlls everything. I think we are going to need some more information like how big, how bright, what colors, how many lights(one front, one back, one on top.....), will they be inside or outside of the vehicle, what do you want to power them(truck battery or AA or other cell), do you have a host for the lights or are you starting from scratch?