Since the shop has an item limit of 255, all the items have been split into "pages". 
To change which page your game loads, rename the files. 
The file that the game loads is "shopList.slt", so if you rename "shopList_page2.slt" to "shopList.slt", you will load the second page in your game.

NOTE: It is impossible to buy Deviljho, Kulve Taroth, and Lunastra parts, as well as other unreleased DLC items, yet. If you try, you will just waste your money.