Should be able to get invoice pricing from Edmunds:
http://www.edmunds.com/bmw/x3/2013/o...tyle=200420854
Make sure you get the MSRP to match the price you get with the build-your-own page on the BMW site - Edmunds will sometimes double count items that are included in packages. I paid $200 over invoice for my '12, but several dealers in my area were not willing to sell it to me at that price, so I don't think $500 over is terrible.
I would highly recommend carbon black. Make sure you see it in person - you may not want to do a matte wrap after you see carbon black - pictures do not do it justice.
Good luck!