I have been micro chipping my pups for over 15 years. I have a potential buyer ( NOT) stating it is against the law for me to micro chip my own pups, that a veterinary must do it.
He sent me an article from 2008 where it states the law was going to be changed, but I have not been able to find anything more recent and I am not paying a vet to do something so simple.

First of all, tell him you have no more available pups but thank him for his suggestions.

I would then check into your state laws but I highly doubt he's correct. You already looked online and found nothing recent. Those type of laws are usually done by city or town, maybe county but not for the entire state.

You could check with I think the Department of Agriculture in Florida. If there are any state laws I would think it might be through them. As I've never dealt with them in my state, I don't know enough about them. I've heard the Dept name thrown around by others referring to their interaction with some high producing kennels or breeders.

Don't agitate the person, just get rid of him. You can check things out at your leisure once he's gone. There's always 1 pain in the ass, know-it-all in the bunch eh.

What I recall is the Florida Dept. of Agriculture's rules are that the puppy should be sold with the micro chip but nothing about a vet being required to insert the micro chip.

I agree with "Get Rid of Him" and tell the guy you don't have any puppy available. This guy will be trouble for you. I have told a few to find another breeder recently myself they are just to high maintenance. I have made the mistake before of over looking some of the little conflicts I have had with puppy buyers and sold them the puppy later and regretted it. Now once I feel like someone is going to become a problem, I cut them loose right away.

Dump him!!! He will be a nightmare for the next 15 years!

Sounds like we all have the same advice. It's your decision what to do but I think you were strongly leaning that way.
He'll be driving you insane if you keep him. We all like the *nice* families that send holiday cards yearly with the dog in it and call us for their next pup 14 years later. Not the ones that have a complaint a week possibly returning a 6 mo. old overweight, untrained pup. I've only had 1 of those and never want that to happen again to myself or any other breeder. He's put out the big red flags.