How much fab skills do you have? Strut type bags aren't too expensive, and the rear bags are actually pretty cheap. You would need to make mounts/perches, plumb it all up, wire up the solenoids, and get some type of air supply. Bag systems can be done well, and cheap, if you have the skills and tools to build up all the parts that make it fit to the car. Most bag companies will help you choose the right bags for your application. The rest is up to you. I've helped bag a few trucks, and one car, and it really isn't that difficult as long as you get the right bags, make sure nothing will rub on them, and do your homework for how to set everything up.
