Do local mobile phone stores make a lot of money?

I am looking into the Galaxy Ultra 26
It seems like there is a price difference of about 300,000 to 500,000 KRW
between regular local stores and "holy grail" (discount) stores
Even regular local stores seem to have a difference of 100,000 to 200,000 KRW
For a local store to cover rent and labor costs, they would need to make at least 300,000 KRW in profit from someone like me, right?