I have owned a 2 natural gas vehicles. The first was a '92 Ford Ranger that was a former govt. fleet vehicle. It had an older GFI system. The manufacturer was either out of business or just didn't support them anymore but it didn't matter since the system worked pretty much flawlessly other than some minor adjustments I could do myself.
The second was a '99 Honda GX. It also ran perfectly never needed to service the CNG system.
I have never heard of a do it yourself system. The system is, obviously, compressed. It is a sealed and pressurized, not really DIY type stuff, not even stuff regular car mechanics will work on.
Here is a link for Fuelmaker which produces the home filling station.
index It is not Honda specific.
Last I checked they would only fill at low pressure which is OK as since you are at home and probably not in a big hurry but would mean that you would not be able to go as far on a tank. They must be installed by a licensed professional and are not cheap.
The cars have advantages of being cleaner in the emissions but also just the dirt in the engine. They need oil changes and other maintenance less frequently. An engine that runs on CNG should last longer.
The down side is
Lack of fueling stations, Many areas have none. For me it meant a about a 15 mile drive r/t when I wanted to fill. That wasn't bad when I was commuting past a station, it was a lot of gas and time wasted to fill up when I wasn't.
Cost, home fueling stations are expensive. Buying it the pump in my area (SoCal) was expensive. I don't know the current price but it was costing me more than regular gas would. In other states it is much cheaper. When a particular company took over almost all the stations around here the price went way up, they had a lock on the market.
Range, yes, the vehicles get about the same MPG as a regular car. They typically (unless you upgrade to multiple tanks) don't have the range of a car that runs gasoline. I believe I filled my GX every 150 miles if I filled it at 3600 PSI, I would get less if I filled at 3000 PSI. You don't want to run out, no one can "bring you" a gallon of gas, you will need a tow.
Public perception, people are scared of natural gas. They think it is going to blow up. It is actually safer, unless your vehicle leaks in enclosed space the gas will quickly dissipate, not pool like gasoline. However I met lots of people that were convinced I was a rolling bomb