Most of us on this forum know to stay away froma 1st year 1998 C5 with a 2 point slow engine.

Are you getting another car?I suggest stripping down everything extra you put on your current A6 and thowing it on the wider,more muscular4.2V8 version.I see appearance matters to you so why not have the looks and a whole lot more power. You'll be happier
Doing a private saleand getting the price you want can take time.If you can't wait, find out what a dealerwill give you for it. Run down what you did. Doing the timing belt is a huge +
Keep in mind your car isnow 9 yearold. So don't betoo suprised if they give you only $7K for it.