Question

why goods sold in permanent shops are costlier than those sold in the weekly markets

Answer 1

there are various reasons for it 
1. weekly markets sell goods in mass
2. These have low cost of running like permanent markets have to pay much rents, electricity bills, brokers would ask them for money etc. etc.
3. Weekly markets do not sell a high quality product most of their products are fake and they sell them under renowned names. People buy a lot because of cheap prices.
4. However the margins for weekly markets are less whereas permanent markets make lot of money by selling less but adding more prices.

Answer 2

There are many reason behind goods sold in permanent shops are costlier than those sold in the weekly markets :-

1) Weekly markets do not require permanent shops.