Its also important to keep in mind often retail stores are forced to give sales because they are desperate to stay in business and can make very little to no profit on the sale item. He might be struggling to stay afloat to feed his family and support himself. While this might not apply to him and doesn’t mean you have to shop there its something to keep in mind. I also hate when stores do these things but I can also sympathize with the owners.
Most business owners making plenty of profit would honor the price to make the customer happy. The fact that he didn’t probably means he cant afford to and his business is not doing well.