They propose to promote your brand. That's how these negotiations actually go. Asking a question like that signals that maybe nobody needs to pay anything to anybody. In these situations firms can't begin to account for the nickels and dimes in the deal and may not even bother trying. In these situations, relationships triumph over transactions.
Money drastically diminishes as a factor in the deal.
The very concept of the customer begins to disappear. Look at Silicon Valley. Every major firm there is a node in a complex network in which a huge fraction of the value creation could never be accounted for in monetary terms. No wonder, because all their measurements are expressed as units of money. Unless some dough changes hands, even the biggest commercial developments are as unheard as trees falling in the distant forest.