Install Airbag's on a 89 Firebird?

My son found an 89 firebird online for a good price, but it dosent have airbag's his birthday is comeing up, and i want to get him a gift he will really apriciate, but i still want him to be safe is it reasonable to think about installing airbag's or would it cost me a fortune... (i have no clue what it would take to install, so any details would be apriciated..)