There will always be costs as you know and Audi's are not cheap to fix even at your local Indy garage , might be worth having a walk around your local area and pop into some Indy garages asking how much they charge an hour but don't mention the model off car unless asked as you could be charged more for aging a Audi .
There are things that you can do yourself if your mechanical minded ,is changing oil, brakes etc, but what I would say is see if you can get a hold off someone who has a genuine bag cable and ask the seller if they mind you plugging it in so you can see if it has any faults or if there has been faults what ones they where ,
Loads off info on Google to find out how you can tell if old faults have been cleared . Hope this helps