20K is a pretty good price for an EB MKS. Build cost of wheels & tires into your offer price.
Bent frame/suspension/alignment should be checked for pre-purchase. If they don't allow verification by an independent mechanic/body shop, lower the offer price. Hopefully it's just a fascia issue.
It's a NY car, so it's likely seen a few tough winters. Inspect for rust/water leaks. Is the paint in good condition or is it all swirled up? The trans/PTU/RDU fluids are probably original to the car, take a close look as you have no idea of the prev owner's driving style. Not a lot of miles on it, possibly quite a bit of city/local driving.