Years back I was in a band with no budget. For lights we went to a wholesaler and bought 24 reclaimed recessed ceiling cans for a few bucks a piece. We used conduit clamps on the front of them for gel holders and ladder hangers put together to hang them from a truss made of old TV tower. We used lamp cord and cheap plugs to wire them to a homemade box full of stomp switches. It was done very cheaply and when all said and done, didn’t look that bad with the lights out in a dirty bar. When we made a little money we bought a small light board and dimmer packs and then eventually bought a bunch of chrome PAR 56’s on aluminum tripods.
The first thing to realize when you step into the world of lighting effects is that traditionally, light are going to be your absolute largest power draw- way bigger than your PA, your stage amps, and anything else you can throw up there. In fact, stage lights will draw so much current that most bars won’t be able to support much lighting (if at all). Expect to flip a few breakers.
That said, technology is finally starting to catch up. High efficiency, low wattage bulbs are finally starting to infiltrate (albeit slowly), and LED cans are slowly starting to come up to spec with PAR cans, and with far less power consumption. Unfortunately, the price is often prohibitive.