Well, if you want brand new you can get a 2004 A4 for $26K....the 1.7L Turbo. The 3L 6cyl is $5-6K more, which might afford you an upgraded turbo and chip on the 1.7. I'd probably go with the Cabriolet just cuz I don't like 4doors.

Of course, I like the S4 over all of them.

I still think all of them are better options over the other car you were looking to buy.