What's needed to replace airbags?

I've found a totaled 2004 tl and I'm trying to decide how much it's going to take to rebuild it.

The main thing confusing me right now is what it's going to take to replace both driver and passenger airbags.

While pricing airbags from several places I see the seat belts and airbag modules are sometimes paired with the airbags, so is it required to replace those as well or can just the airbags themselves be replaced?

Thanks