What is the cheapest device I can use to download a flashcards app from my iCloud?

I assume it may have to be a smartphone, but I need a separate (very cheap) device just for viewing my many flashcards on this app for revision purposes. I want to use a desperate device to my iPhone 5 to revise my flashcards without the need of any other features on it. The screen would need to be at least the same size as the iPhone 5 in order to render my flashcard material properly. I would rather not simply use my iPhone because I spend a lot of time outside and need to revise outside during the winter, and I worry that exposing it for hours in sub zero temps will damage it. It cost me £600 and can't risk that. Any cheap alternative device to download flashcards+ from my iCloud would be suitable. If I know what to go for then I can simply search for a used one on eBay to get a cheap deal. Thanks for your advice.