Keep in mind that the process for DCF is a bit different for each embassy based on the country the DCF is filed in. The Embassy /Consulate provides clear instruction on how to make payment, the amount, and process once they allow you to file in person. Regardless, the fee is the same amount across the board for an immediate family member. With that in mind some embassies allow you to pay in US dollars or using debit/credit. When we did DCF in Germany we had to mail in a US cashiers check with the I-130, I-130A and requested documents. For most this is tricky if you are living in the country where you filed DCF. This is when you ask family/friends to get the cashiers check for you and send it to you so you can make payment if it has to be mailed to the embassy and they don't take in person payments.