Got the X5 for 52K, Edmunds invoice was 55480 (52885 w/o Prem), so got it about 900 below invoice. The dealer had lots of X5 on the lot and he told me he was taking a loss on the vehicle. I think there is a lot of demand for the upcoming xDrive35d (diesel) that is launching in the US for the first time as an 09 model and thats why they are not able to clear the inventory. I would suggest using the following equation:-
Invoice - Premium Pkg Inv. = Good Price - Something = Even Better

Love the drive, it's awesome, way better than the 05 outgoing model I think. Looking at the oil prices fall off late makes the grin on my face even wider, I hope the oil speculation bubble has finally burst. BTW, I do have a green streak in me, hence I carpool, and my carpool buddies, both 6 feet + love the leg room they got compared to my 3 series