Don't get an 01 to 06 S60 automatic, especially an 01 and 02. Transmissions should have been recalled though you can flush, update a servo cover and get the latest software update from Volvo, let the transmission learn how to shift again and may be OK. Roll of the dice.
My current daily driver, an '01 with 94K on it. Check out the video. 17 quarts flushed and filled to get it red. The cabin filter...dealership said they changed it 3 times in last 10 years.
https://www.flickr.com/photos/132859093@N05/sets/72157655224261880/