Help with negotiating results of a Home Inspection?!?

The "person" buying my home wants $12,000 in repairs (largest items: Radon Remediation (we are at a 4.6) $3000, a Chimney Liner ($3000), and ... they are claiming there is POSSIBLE Asbestos inside our ductwork ~ it's non-visible for $3500 (we had a company come out ALREADY and remove Asbestos, for $4000, and issue a Clean Air Certificate. They claim there may be more, they missed?!?) Our Attorney is giving us the impression that these items aren't negotiable (we know the Radon isn't). We always thought this part of the process WAS negotiable? Any thoughts?!?