alot of imports

(turbos and NA's) have it already fitted if you havent yet bought the car

from memory you'd need

the condensor rad
the aircon matrix thingy in between the heater blower and the heater box, aircon equipped heater controls

(as far as i knoww these are all electrically controlled as opposed to the cable operated non aircon ones) all the pipes from the front of the car and under the fuel tank
the compressor

- the crank pulley will already be there for the aircon compressor belt

(certainly has been on all the non aircon cars i have seen)

probably cheaper and less grief to buy an ice lolly every day