To download apps from the US app store, you need to create a US iTunes account. By following the steps below, you will be able to create an account without needing a US credit card.

• Start iTunes on your PC/Mac and go to the US appstore
• Try to download a free app
• Select the option to Create New Account in the popup that appears
• Fill in your details and in the Payment Mode section, select None
• Wait for email from Apple confirming that your account has been created

In my case, I had to wait 2 days before I received the confirmation email from Apple. If you need to buy apps, just top up your account with iTunes gift cards. One way to obtain them would be through eBay from a reputable seller.