I wold also like to have this done but I know that it costs a lot of cash to do it. As of right now I doubt I have the funds to do it. But if anyone has an estimate for an 04 Maxima and a 02 Ford F150 I would appreciate it.
You can get loans from some places for this. I know CNG of OKC has some sources for financing. The one I'm putting on my truck is around $8K depending on the tank I pick if I ever make up my mind. The base system (CNG/Gas) and install for a V8 is $6500 but does not include a tank. You pick what tank you want and add that to it. You can spend $4K+ on just the tank if you want. A class 1 13.8gge tank weighs about 400lbs and is made from CrMo steel thats dang near 1" thick. The more $$$ the lighter it will be.
The pump right by my house is priced at $0.79/gge. Just sayin... And yes you read that right, it is in fact a zero...