Airbag light could be a very simple issue; on my wife's old A4 (of slightly older vintage) a dirty/corroded connector under the seat - a known problem - caused the same fault.
I pulled the connector apart, cleaned the contacts, plugged it back together and cleared the fault with VAGCOM cable - problem solved. Do a google search and see if there's a common problem like this with this model. Chances are if it was widespread on the A4 saloon and Avant, it's going to occour on the vert.
The airbag light coming on because the battery was disconnected is bullshit. The seller simply can't think of another reason that doesn't sound expensive or the actual reason.
Gone but not forgotten:
325i M Sport (E92), Black Sapphire, Coral Red Dakota, 19" 225's, Seat Heating, 6FL and de-badge
Replaced by 6.2 litres of AMG powered C class.
Last edited by sheps; 01-09-2013 at 04:42 AM.
Reason: correcting formatting errors created by sausage fingers and iphone combo which made it look like Borat had written my post...