I bought a climate control unti for an A4 (B5 2001) from ebay with the anticipation of swapping the whole unit for my s3 (8L) one, but it's not the same part.
The part number is 8D0 820 043 Q and all the buttons are in excellent condition. I have not tested the unti as it would not fit my s3, but the ebay seller has assured me it's working. Worst case scenario, if you have worn buttons on your unit, you can just swap the buttons over (they just pop out with a flat bladed screw driver).
Only £35 - you can pick it up from me or I can courier it to your for £5