they also have a steering damper as well but for some reason it wasn't included on this page. I just recently ordered all four shocks and steering damper for $442 and change from these guys.
Front airbags. You can do these yourself from down below. If you are having a garage do them and they are dropping the suspension to get them, I'd replace the springs and lower ball joints as well while they have the suspension apart. Lower ball joints especially, as when these go, it is a very bad thing to have happen and can be very expensive to the bodywork.
As for rear bags, yes that is the number. Be prepared for the biggest PITA job you'll ever do. How do I know.....my buddy John just did his 325, and ended up cutting two 6" holes through his floor to get at the rusted bolts and seized air fittings.
Goodluck, and you may want to have the garage quote you on replacing them, as opposed to having them charge you per hour. Be prepared for a very large bill!