I think this customer is trying to convince you that your prices are too high, by having "several" fake customers offering you low-ball prices. My advice is to ignore them. If you think your prices are fair, you can disable "Price Offers" in settings and not have to deal with that. I've disabled it months ago when some customers started low-balling me. If people don't like my prices, they don't have to buy my models. I'm fine with that.