Your gas price link, residential price is about $20 per thousand. $3 is a trading price not a consumer price.
Natural Gas then compressed to over 3,000 psi at a vehicle fueling station is going to be around $2.00~$2.50 per gasoline gallon equivalent. Possibly more in markets like California.
That's not the information I'm getting from my local gas company. You may or may not know this, but if you have a large amount of gas usage, you can buy your supply on the spot market, and pay a transport fee to the gas company who's pipelines you use to transport the fuel. You do not have to buy the natural gas from the company that owns the pipes leading to your application.
It is no difficult task for a large user of Natural gas to buy the fuel on the market to supply their own stations. A large trucking company could easily manage the usage necessary to make this worthwhile.
I'm shooting for a sell to the public price of $1.00/gallon for my own station. But for my own usage, i'm expecting the price to be around 50-60 cents per gallon. I'll find out soon how that's going to work out. My output pressure is going to be 3,600 #.