Not sure what to do.

[Kracka]

Harnesses in a daily-driver with no roll cage will probably be more unsafe than regular seatbelts and no airbags. What if you get T-boned? What if you roll? If airbags are a must for you, look into getting a 2G instead.

KBB values really don't mean anything when it comes to used DSM's; they are an enthusiast car so they definitely hold their value a bit better than the average car. Any more details on the car you're buying?