Thanks for responding! Do note though that I will be buying it on Steam when it comes out since I prefer not to use my debit card online due to privacy concerns.
You can buy Steam Wallet Codes in retail stores that sell them. They work much like prepaid SIM load cards where you uncover the codes by rubbing a coin on a special area which will reveal them. Afterwards, you can enter them into a page in Steam which will credit the pre-designated amount (such as a $100 Steam Wallet code) to your Steam Wallet.