6.0GOAT

I've been looking at a WS6 on craigslist, and on the ad it says that the heater and a/c have been removed for weight purposes. However, these 2 are crucial to me, as this car will be a DD. How hard would it be to install these back into the car?

How pricey would this get if I do it myself? How pricey would it be if I was to just pay someone to do it?

Thanks!