Counteroffer Question.

I had purchased some items from eBay and sold them on Amazon, the lawfirm that protects their intellecutal property sued? me and now is asking for 6k per item that they said is counterfit. They are requesting that I pay 30k in total.

I made 6k last year on Amazon this is a very high number for me to have to pay and I simply do not have it. My legal team is asking for a counteroffer, and I am wondering is there a standard pratice that maybe I can request 20% or 40% of their ask and it generally will be accepted?

Simply any advise would be great, I did not know or suspect the books to be counterfit when I sold them.