Is this a "new" 2013 A4? You can appraise a new one here like Texases said, just go to the New Cars tab and drill down. I come up with a TMV of $40,487, assuming I have your options correct. That number will vary some by zip code. And there's some incentive money you may qualify for on a new one.
First year depreciation on the A4 is about $7,576 so that may affect your thinking. All cars are "used" once you drive them off the lot, but this one has already used up half of its first years depreciation.
But I dunno - it seems like you could do a bit better, but from reading posts around here for years, my feeling is that dealers don't like to deal too much on demos.