I think the price a tad high but in the ballpark. Justified or not the ZHP package does bring the cost up in terms of purchase. In terms of ownership costs it shouldn't be any different than any non-M E46. I knowingly (and reluctantly)overpaid somewhat for my recently purchased 6MT '04 sedan with a ZHP package but it only had 52K on it and I plan to keep it a while. Furthermore, I didn't have to travel to get it and that cost is easily overlooked. Finding exactly what I wanted here in Albuquerque was unlikely at best and was probably worth $1500 in travel and 2 days of leave from work. I think the biggest thing to consider regarding price is how long you plan to keep it. (within reason of course) Two things of caution I will pass along as a newer E46 owner- I'm struggling to get the kind of mileage I should be getting and if you desire an LSD be aware that there are not the cheap and easy options for these cars that there are for your 635 -or my
E30. I still really like the car but this last point is a bit of a bummer for me.
Be sure to check the strut towers for crowning. They can be fixed but you should negotiate the price if they need it.