Ball joint replacement

I have two questions:
First: Do ball joints usually wear down evenly, or is it common to have to replace left before right, upper before lower?
Second: How much should I be looking to pay for this at a local mechanic. I gave Firestone a call and they want $650!!!
Thanks

wow!!! 650, where are you located? That's high for around here...I had an estimate done to replace all 4 on my 88 and they wanted 250. But I am in southern Indiana. I did them in my backyard with a press and a balljoint seperator for about 25 a balljoint, rental on the press ($99 you'll get it back after you return it at autozone), a balljoint seperator, a nice big hammer, floor jack and a set of jack stands. It took me about 8 hours to do all of them, but I was in no big hurry either.

You will find that the passenger side ball joints will be the first to fail. This is due to the fact that that is the ditch side and more roughness is there in driving. As to whether the upper or lower fails first, it depends. In my experience, I found found more uppers before lowers. Usually replace both since they went for the same ride.

you dont say what year/model but if it is 88 or newer, it takes about 2 hrs per side if still riveted plus about $50 per joint.