Well you can always bargain the price of the black one down some, maybe try 1200$ first and see if you can meet in the middle for maybe around 1400$. For 1400$, it looks your getting a steal anyways! No engine or transmission problems and no dents. Basically need a new paint job and your set. Paint job can cost you 600$ or less depending on who you talk to and you supply the paint and everything. If you even want, you can spray can you car also, it's been done. I would get the black one for sure. The amount of $$ your going to spend getting parts ect for the iX, you can get lower springs and such for the E and make it look all pretty.
Only reason why I bought my IS was because it doesn't need engine nor transmission work. Body/floor work is nothing but once you start with the engine it can get costly.