Before , sir , buying a used e83 X3 bear in mind that the engines have a lot of problems as they age.Search the forums and youtube before buying one as they are not cheap to repair . Also consider the fact that every 6 to 7000 miles you will need an oil change plus the filter.They are not reliable and they depreciate their value fast.If i were in your shoes please allow me to suggest the Japanese auto makers.I put the link of an X3 2007 3.0 owner and what he has paid.
https://www.youtube.com/watch?v=Aue_nKDD2pQ&t=20s