I bought an Audi Certified 06' A4 2.0T Quattro 6sp MT with 18k for @26k in Feb of 08. Some might find it cheaper, but getting additional warranty was key.

SB Ridge

 

I own an A4 2.0t quattro and the only major problem are the bixenon headlights. mine are malfuntioning all the time. sometimes it's like a light show outside the car until one of the lights go out . Then I get the warning light on the dashboard. It can be either light. When I stop the car, shut off the engine and turn the lights back on they are ok. The dealers response is to replace the ignitors and bulbs on both sides at $2000 per side.

 

Got mine at the end of may this year. 2006 A4 2.0T Quattro MT6 CPO, had 30k miles on it. Came with 2 years left on its warranty and an additional 3 years 100,000 warranty $24k @ 1.9%.

So far I'm LOVING the car. I used to own a 2005 Nissan Altima 3.5SE, and while that was a quicker car, I can't begin to tell you how much more fun AWD is. In addition, it's much more refined and well crafted compared to the domestic and japanese counterparts. I average about 28mpg, but that's mostly freeway with some city. I took a trip from sacramento to LA and i recorded about 32MPG while cruising with myself and a passenger @ 80mph with A/C on.