Why don't you buy an extended warranty from Audi UK for the same price as the air suspension strut which will cover the car for a whole year.
Only drawback is that you cannot make a claim within the 1st month of buying the policy.
Check it out and read their T&C booklet carefully
https://insurewithaudi.co.uk/extended-warranty/
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Previously:
2010 Audi A8 4E Quattro Sport TDI Oyster Grey
Currently:
2015 Audi A8 4H Sport Executive Quattro in Monsoon Grey