WHICH IPAD IS THE CHEAPEST

Price will depend on storage capacity and wether you choose the cellular model or not. Starts at $329 USD . You can see pricing and options in the Apple Online store: https://www.apple.com/shop/buy-ipad/ipad-10-2

Get a rugged case for it while you are at it.. https://www.amazon.com/Child-Proof-Case-iPad/s?k=Child+Proof+Case+for+iPad

Of current models, the iPad8 is the cheapest model iPad.