I replaced my water pump and thermostat this past weekend, total cost was just under $450 for parts at www.thebmwpartstore.com
plus about 6 hours of my time (took my time, ate lunch, put the chain back on my son's bike, etc). I only had a jack and jack stands; I agree that a lift would make it much easier but it can be done without one. My only suggestion would be to remove the sway bar completely (it's only 2 extra screws), don't just let it hang from the end links because I knocked the shit out of my head on it
. I did not take out the radiator fan either. All in all this is a very doable diy project that will save you a lot of money.
To quote the great BMW diy'er smolck (and an old movie from the 90's), "what one man can do, another can do!" Save yourselves some money and tackle this project guys!