This is an awkward question, because the honest answer is it depends.
We have to offer the best number we can, because we don't want you to go to someone else.
That said we offer a service, that service empties your space and puts cash in your pocket.
It may make you money, it may release cash from inheritance, it may allow you to pay your bills, stop paying for a storage unit or sell a house.
Unlike a plumber or a hairdresser or any other service provider, our service doesn't cost you any money. No cash leaves your hands.
You pay us out of the equity in your item.
Whether we pay fairly, depends on how much equity you feel is fair to give up for the work we do.
If you are prepared to give up 5% of your items value, you will likely call us a bunch of robbing ******** for the amount we would offer you.
If you are willing to give up 90% of the item value for our service, then you will absolutely love our offer and think we are the most generous people you will ever meet.
The reality is that we sit somewhere in between those two extremes.
Whether our offer is fair or not is a matter of perspective.