I am looking to buy a 2003 Grand Marquis that does not have the keyless entry option

When i asked the seller does he have the key fobs, he said he doesn't,and he didn't think they would work on the car (his elderly fathers car).

Even if he doesn't produce the fobs for the two keys that come with the car, do you feel i would be able to purchase 2 fobs and have them programmed to work on this 2003 Marquis?

Thx for any help!!