Divorce rates are dropping, according to the National Center for Health Statistics, and money--not love--may be the reason.

In the 10 months from January through October 1982 there were 980,000 divorces, 36,000 less than the total for the comparable period in 1981. The 1982 divorce rate was 5.1 per 1,000 population, compared with 5.3 in 1981. Over the past decade, the divorce rate has risen or stayed the same each year until peaking at 5.3 in 1979.

Since then "it's been fluctuating," says NCHS demographer Barbara Wilson, "and may be on its way down."

The decline may be a result, she says, of "the baby-boom generation moving through the ages of highest likelihood of divorce."

Others see the "two-can-live-as-cheaply-as-one" adage as a factor.

"I've seen people staying together just because they can't afford to get divorced," says attorney Deborah Luxenberg, a member of the D.C. Bar Association's Family Law Section steering committee.

"With one of my clients trying to work out joint custody, the main problem was how to manage the high cost of two households. I've seen older women who've never been out on their own end up staying in a marriage even though their husband is involved with another woman, because they don't know how to go about getting a job. And houses these days are hard to sell."

A divorce can cost anywhere from several hundred dollars for an uncomplicated, uncontested one, to tens of thousands of dollars for complex, contentious cases. Attorney fees in the Washington area "vary wildly," notes Luxenberg, from $50 to $200 per hour.

While 12 hours of an attorney's time could suffice in an agreeable, relatively simple split, difficult divorces could take "well over 100 hours."

One reason for the increasing popularity of divorce mediation is that it is "usually less expensive" than the traditional route, says Sarah Grebe of the Family Mediation Association.

Trained mediators charge from $45 to $60 per hour to help a couple formulate a separation agreement: average time 11 hours. There may be additional costs, such as services of an advisory attorney--generally $250 to $500--and financial consultants.

For mediation to be successful, the experts stress, the divorcing couple must be able to communicate and reach an agreement with one another--which eliminates some couples from the process.