Most agents will try to convince you the house is worth more than what you think it is worth not because of the delta, but because of the base commission. In general, if your offer is not the highest you will not get the house and the agent will make no commission.
You can probably get someone to work with you on an hourly basis, in which case they don’t care if the house sells high or low. You get in a position that people who deal with lawyers are in – the contractor’s incentive is not for you to win (or lose), but to keep playing.
