Need advice on buying used Prada purse

[GeekChick]

At the high-end consignment shop I frequent, the shopkeeper recently got in a Prada canvas and leather bowling tote (I think it's BL0219).

The only problem is that the previous owner spilled nail polish inside it and, not thinking, had the lining replaced. So it no longer has the Prada lining. The shopkeeper agreed to try to sell it for the owner, but she doesn't know what to price it. She told me to make an offer I thought was reasonable.

The problem is that I don't know what price to offer. Any advice??

[GeekChick]

If the purse is BL0219, then its retail is $800. Given the circumstances, I'm not sure $400 is reasonable. The shopkeeper rarely prices pre-owned items that high - the most expensive purse she has is a huge, vintage Chanel bag in mint condition for $600. Most of her Prada bags are priced in the $200-$300 range, with the exception of the brand-new ones, of course.

Also, since this purse is not only used but also doesn't have the Prada lining and comes with no dust bag or authenticity cards, it has little to prove its authenticity, which is why the shopkeeper was hesitant to try to sell it at all (she knows the woman who owned it and knows it's authentic). I would have a difficult time reselling it if I ever decided to.

But I don't know - maybe $400 IS reasonable in this situation. I honestly don't know. That's why I need some advice.