It will be chaos.
Normal stores will start buying from the state shops, to resell.
Rich people will go to state shops, just to get the bag.
The state stores won’t run efficiently, even before the 30% lower prices are applied. Let’s say a normal store sells $1m per month, with a 5% profit. Your state stores are going to lose half a mil each, per month. 5 stores, is $30m a year.
The normal stores will either close, or only sell stuff not sold by the state stores, so choice and availability will go down.
The state stores will ration stock, so will look like Russian stores.