Xenon Valkyrie+

The store is found at the very right of the hub when first starting a game. Items in the store cost teamerite which is only found in the chests after defeating bosses in game. In my experience the price of items varied from 6-10 teamerite per item so I would recommend saving this until after you've done a few of the runs required for the completion.

Lastly: once you buy an item you can quit to the main menu and retain your teamerite as you won't really need any items if you're planning on using the cheat code to max out your stats.