Instructions
Go to the Cheat Menu in "LEGO Battles" via the main menu. Tap "LEGO Store," then tap the red LEGO brick to enter your cheat codes.
Use the virtual keyboard to enter "HJCRAWK" for the Invincibility Cheat or "ABABLRX" for the Regenerate Health Cheat. Either one of these will make your hunt for blue studs easier so you won't have to worry about getting attacked as you search.
Use the virtual keyboard to enter "CPLYREK" to reveal all of the blue studs available for collection. These will show up on your map while you are in any of the game's levels. Revealing the blue studs on the map makes it so that you don't waste time looking in places where there are no studs.
Pick any level in the game and collect all of the available blue studs. Repeat until you have the necessary amount of studs to purchase the item you want.