Buying 2nd hand bag

Hello everyone Wanted all ur opinion in this. Am buying a prada bag from my mil. Bag ori price is 2500$. She only wear it once. The thing is,she is not putting any price on the bag. She said that she will take whatever amt that i will give. Asked mr husband how much should i pay,he replied,half the ori price. Since its already 2nd hand,no matter what is the condition of the bag or how many tines it was used. If you are the seller, how much will u sell it for?