Unfortunately, they will lowball the number because they want to buy it at a discount and resell it at a profit. I would rather pay for his services for insurance purposes than if he thinks he is going to buy it.
Of course they will. I used to buy & sell antiques on the side. Sometimes people would accuse me of buying low to sell high. I would tell them - yeah, that's the idea.
It's no different than a pizza place charging more for a pizza even though the dough, sauce & cheese do not cost that much. No different than any other business or industry.