Where are the military generators available? Steelsoldiers website has lots of information & govtliquidation.com appears to be the go to place.
SteelSoldiers.com is loaded with info on the gensets. govliquidation is the place to go to bid on them, usually they have an auction a week all around the country for them. Some are 3KW, some are 5KW, 10KW, HUGE units beyond that, and some ones already mounted on trailers. I would HIGHLY recommend previewing the lots before bidding, or have someone close to the auction site do it for you. Sometimes there are missing parts or problems that can't be seen in the pics, so a eyes-on-site look would be much preferable.
The Hondas are, though, very quiet, I can attest to that from camping trips I've been on where friends have had them, and you can carry on a conversation next to one without raising your voice. The military ones, you can't carry on a conversation next to one without loudspeakers.
Be advised - the ratings on the military gensets are different than civilian ones. They are rated conservatively, they will run at rated spec in the worst possible conditions with crappy fuel. In optimum conditions with good fuel, the 3KW unit will put out about 4.2KW, the 5KW unit will make 7.5KW, and the 10KW unit will make 13.5KW.