$1000 for the conversion kit, tank, and rack would be ideal, at $4 for gas and $1.25 for CNG, the cost would be recovered in 18 months or less. But what turned me off when I was researching it was the lack of stations and the cost of compressors. I saw about the "Phill" system, but people trash talking it on a few of the forums. Say
CNG Refueling Compressor DMC-3/200 (3.0Nm3/h) | eBay for example. What is the best way to get the liquefied natural gas to it? Will the gas company leave tanks for you to hook up to it, or do you tie it into the house's supply? I'm guessing it wouldn't be as cost effective to use the house's supply because of the ridiculous gas recovery fees and other surcharges, but it would be more convenient.
Also, from the maps I've seen, why is there such a disparity in price? In Indianapolis there are prices from .88-$2 GGE, is the market that illiquid that the prices vary that much?