Product price strategy

Hari runs the retail shop
Once he gave a discount to one customer

Everyone started asking for a discount
Hari has to spend quite some time with each customer on negotiation.

He realizes the waste of time and effort in doing the negotiation.
He put the board “No bargain, Fixed price”

Still, the customers keep asking for the discount
He let go the few customers

Once Customer expectation is set
No one asked for the discount again.

Set the customer expectation right from the beginning.

Thoughts?