The Item Shop is referencing the Cultivate Shop, in which you can buy various materials and items with in game money. You can access this menu via /shop. Users are able to buy most items in quantities of 1, 8 or 64. Users are also able to fill their inventory with the items as well.
In most scenarios, using the Item Shop is going to be the de-facto way of getting things. It is much quicker than naturally collecting/gathering items.
The main philosophy that is adhered to in regard to Item Shop balance is to create a version of the shop which is moderately challenging, but has a wide selection of items and is stable in price. Survival is meant to be a more casual gamemode, and uselessly grinding for items is not something that is in the best interest of the player due to the other elements of the game that require grinding.