yes, but what's "full price" on a used car? Isn't it really whatever someone is willing to pay and the owner is willing to let it go for? Obviously, the buyer has to make his/her own assessment that include the condition of the vehicle. At a minimum, here the OP can argue that the $86 was the price with no damage. He didn't see it and they didn't disclose it. I'd also try asking the dealer to inspect and warrant that there is no other related damage.
If its just the bumper skin that isn't that expensive to fix, when looking at an $86K vehicle. Agree with other's comments on making sure there is no other hidden damage as there could be.