The price you pay for using the wrong ATM.(up front: News/Trends/Advice)

Your bank's cash machine is out of service, so you stop at a competitor's. That decision may cost you more than you realize. Using another bank's ATM just once a week could easily cost $100 a year. That's because not one but two banks usually tap your account for fees.

Easy-to-miss fees have hit a new high and are more prevalent than ever, according to the latest survey by Bankrate.com, covering the 25 largest markets in the U.S. Not only do 81 percent of banks surveyed charge an average of $1.29 each time their customers use a competitor's ATM; but now, 98 percent of banks that operate ATMs add their own fee for users without an account.

The average surcharge has increased more than 20 percent over the past two years to a record $1.60. Some banks charge far more: up to $2.50 per transaction at ESB Bank in Pittsburgh, and $2 at Wachovia and scores of other banks nationwide. Bankrate.com estimates that Americans will collectively shell out $4.2 billion in fees this year for taking cash from competitors' ATMs.

You may not see those fees coming, even when you try to compare checking-account options. Bank of America's Web site, for example, lets you compare options at a glance and touts "unlimited Bank of ...