I assume you didn't purchase from BMW dealer? Otherwise, you would have CPO warranty. I'm currently searching for an '06 with low mileage myself, but prefer CPO...they're fetching between $40k - $43k...non CPO's with 1 year of factory warranty left, are fetching in mid to upper $30's.

I believe once the X5 ///M is released, the E53's will take another beating.