In my state, NY you do not have to have the vin plate on the dash at all, you don't even need the sticker in the jamb (although it makes inspections alot easier) You do however need to have one "permanantly attached to the vehicle chassis from the factory". If you ever got hassled by police for the vin, at least here, they know where to look or they just call the detectives who are in charge of Vehicle theft. I had a civic back in the day and got pulled over by a real asshole of a cop, the dash had been changed in the car so there was no plate, and the car had been repainted so the sticker in the jamb was painted over, he just had me pop the hood and he checked it against the registration and he didn't bother me about it again. He did however impound the car after he figured out that I had a suspended license, and pending tickets. But the impound had nothing to do with the vin plate missing.
i know for a fact that you cannot purchase a vin plate, nor can one be obtained from honda, other manufacturers may be able to get one for you, but Honda gets vin numbers assigned to them by the united states dept or transportation, once a vin plate is created it is not ever re-created. Same with the sticker in the jamb. You can contact honda, or D.O.T. and they will tell you the same thing.
Sometimes you can make a vin plate out of another vin plate by flipping it over and punching the numbers into it and then rivit it to the dash. It's probably illegal, but might not be if you are not trying to say it is something different than it actually is.
On top of all of that, if you do a really good job with making it, the cops won;t even know.
I would do like the others said and try to contact the previous owner(s) to see if they have the original dash or the vin plate.