Big banks are breaking in to the prepaid debit card market, and the subsequent competition is putting downward pressure on fees. Large national and regional banks also are making fees less complicated by offering low, fixed monthly costs. According to a new Bankrate.com survey, 13 percent of card issuers -- primarily the largest players -- now charge a single monthly fee of $4.95 to $7. The structure saves consumers on the numerous charges -- for enrollment, ATM transactions, balance inquiries, and more -- that quickly snowball on other prepaid debit accounts. Still, it is critical for consumers to comparison-shop. "It can be confusing because of the variety of fees," acknowledges LowCards.com CEO Bill Hardekopf. "It's very important for consumers to read the terms and conditions of the different cards they are considering. They should compare the fees based on how they expect to use the card."