If she said she would sell them at the reduced price and drive them I feel she had a deal with the customer. If she did not, that's different. In most transactions of this kind there is no deposit, there is merely an agreement. I would be totally torqued off if I had called someone, they had agreed to sell to me, and then they pulled out, especially if they had already said something like "I guess you can have them for eight each, how about we meet Thursday".
If it was a fishing expedition where the conversation was of the sort where someone asks what is for sale, gets the price, asks if the price can be lowered, and either party says "I'll get back to you" that is different.
If it was a fishing expedition where the conversation was of the sort where someone asks what is for sale, gets the price, asks if the price can be lowered, and either party says "I'll get back to you" that is different.