"How does two shells' worth sound?" He's not much of a haggler, but if he can stretch this supply out for as much as he can and get it out of the vicinity of two children who, he knows (he knows by the sting of the scent in his nostrils, a phantom tingle of memory), are not fond of the scent of the stuff as quickly as he can.

He used up most of his last supply already. He could use a bit more.