Things I'd consider:
2004 C32 - fast, but body style getting outdated
2006 330i -
2006 is350 - not bad, but not German
2005 S4 - exterior isn't my fav, but it's a strong car
2003 CLK55 -> rare, but you can find with under 40000 miles for this price, and better reliability than the C32 given it's n/a
2004/5 CLK500 - not sure how well the non-AMG handles
2005 Porsche Boxter - actually, the Boxster isn't my cup of tea, but worth mentioning
2005(?) Lotus - not really luxury, but really fun and quick
-you won't get a 2004 545 for that price with those miles (at least as of 2 months ago when I looked), but 530i is worth checking out.