This is what I'd be looking at:

http://www.pistonheads.co.uk/sales/3730614.htm

There are lower mileage ones out there for that price, but I wouldn't worry about the mileage on this one, from the ad and photos I'd say it's a very well looked-after car. Only two owners and the engine bay looks very clean. It's also very clean, straight and original by the looks. Looks a lot more appealing than the others with lower mileage.

As for the V6's, yeah S4's represent great value for money, but I'd still be looking at spending a bit more than your budget if I was looking for one of those as parts etc can get pretty expensive.

However, you could pick up a decent ST220 or any number of MG ZT's within budget. The MG may not be an obvious choice, and may not appeal to lots of people, but it's a pretty modern, well-equipped car that's great to drive for next to no money. And it's well screwed togeher compared to the smaller ones as BMW had a big hand in it.

But sounds like you're looking for something a bit smaller and I think that 200sx would be a good buy.