1 rifle and 1 pistol for every member of the family. Preferably common firearms chambered in common calibers.

I suggest ar15s for rifles and just about any 9mm for pistol as long as it's from a reputable manufacturer.

I've built ar15s for less than 300 pre covid, you can still probably do it for less than 400 if you shop around for deals. PSA makes good starter rifles and so is the m&p ar15 if you don't want to build your own.

Any pistol from glock, Smith and Wesson, Ruger, h&k would be a good choice.

Body armor is pretty cheap, you can get a plate carrier and plates for $300 total if you shop around.

Check out r/gundeals so sweet deals.