Fortunately, no federal law and few of our states restrict body armor except during the commission of crimes and for those convicted of crimes in the past, particularly felonies. Connecticut restricts the sale of body armor to in-person transactions but does not outlaw the purchase or possession of it. At least one state, Kansas, prohibits the wear of armor during parades, protests, rallies, and demonstrations, but otherwise does not prohibit its purchase or possession.
Second Chance, significant because of its role in this history of kevlar armor, always had a policy of not selling to citizens and only to law enforcement -- screw them. I think they were ultimately ruined by the Zylon scam and they're gone -- bought by armor holdings which was then bought by BAE. I haven't seen any other brands of armor with that kind of policy.