Airsoft guns are not regulated in this country and any
Walmart or sporting goods store should have them in stock. They have the legal status of a rubber dart gun (i.e. toy) so you may use them wherever and however you wish, although you should use some common sense in where you use them. Most have orange tips or the entire gun is brightly colored to distinguish it from a real gun, but there are a few that look real and I would avoid using those in a public area as someone may call the police.
Also keep in mind the BB’s are plastic and bounce everywhere, so if you use it in a public park you will need to come up with a way to clean them up or you are technically littering. They are fun, we use them in our backyard for keeping the aluminum pop can population in check.
What I bolded above is not true at all. There ARE regulations in some places, mostly at the local level, as to where an airsoft gun may be used. I don't live in Florida, so I don't know the regs there. If you are staying in a hotel, you may have trouble locating a good place to shoot, as you likely won't be allowed to shoot on their property, and some towns/counties restrict airsoft, BB, and paintball guns from being used in public parks.
How old is your son? There are a few airsoft places in Orlando where he and your husband could go and play for a few hours or even a whole day. They generally rent equipment, so you don't have to purchase everything. One that seems to be popular is
http://www.orlandoairsoft.net/. I can't find a minimum age listed on their website, but if you want, I'd be happy to call them for you and ask. Let me know.
If you do decide to purchase one, check your country and local laws on using it at home. I know when we went to Europe last year, our son was 15 and I think he discovered that he was not allowed to play in some countries due to his age.
Also, check to see what, if any, restrictions your airline carrier might place on transporting it home. Within the US, it can be placed in checked luggage without declaring it as a firearm, but I have no idea what, if any, differences there are for international flights.
My son is really into airsoft, so if you have any more questions, let me know here or via PM!