Are there transaction fees on the website?

If you are buying DIO with Visa/Mastercard, there are payment service provider fees during the transaction.

If you are using the game wallet to buy  in-game items, there are no transaction fees.

If you are making transactions from your private wallet, you will require SOL to pay for transaction fees, like any decentralized transaction. This is because these transactions are being executed on the Solana blockchain.