These nonprofit cooperatives could be the most misunderstood bargain in banking. Although they often offer higher rates for deposits, lower costs for loans and reduced fees for such things as overdrafts and checking accounts, many people are confused about what it takes to bank with one.

Many consumers have an old-school notion that credit unions are always exclusive clubs, only open to employees of a single company, or to members of a particular church, union or profession. But with many credit unions that's no longer the case.

There are certainly some that restrict membership. But, increasingly, these institutions have thrown open their doors to anyone who lives and breathes in a particular ZIP Code.

In a 10-minute search, for example, I found five that would accept me based on geography alone. And that's common, said Katye Long, a spokeswoman for the Credit Union National Association, which sponsors a credit union search tool. (Go to www.creditunion.coop and click on "Locate a Credit Union.")

Since the 1998 Credit Union Membership Access Act, which allowed credit unions to broaden their field of membership, thousands of organizations have extended their membership to anyone living in a particular community. And that community can be vast -- all of Southern California, for example -- or extended to anyone who has ever been employed by or attended school in the state.

Of course, if you also happen to be a teacher or engineer, broadcaster, public worker or employer of a credit union-sponsoring group, you can qualify the old-fashioned way, too. That could leave you with access to a dozen credit unions or more.

Why go through the trouble of seeking out a credit union when you could far more easily just wander into a bank? There's a good chance that you could drop the cost of a revolving credit card balance by 1 percentage point if you do. Your new-car loan could be about 1.5 percentage points cheaper than if you financed through a bank.

And, although deposit rates are pretty paltry everywhere, they're about 25 percent better on average at credit unions than banks, according to Datatrac, which does a daily survey for the Credit Union National Association.

Six of the 10 top-earning checking accounts offered through www.checkingfinder.com were offered through credit unions, in a recent survey, said Don Shafer, chairman of BancVue in Austin, Texas.