There's nothing like running for president and being paid for it. That is just what Ronald Reagan is doing and if he seems at this point to have a slim chance for the presidency in 1980, he is very likely to be nominee of the Republican Party and that is his immediatte goal.

Reagan's income has been put a half a million dollars a year. A large part of that comes from his five-days-a-week, three-minutes radio spots carried by hundreds of station throughout the country. His newspaper column is another source of income.

It would be grossly unfair to say that his nationwide public forum is devoted to advancing his personal cause. But it is an unprecedented opportunity to promote the conservative causes that are at the basis of his candidacy.

Besides the returns form radio and the press, he makes from seven to 10 speeches a month, for most of which he is handsomely paid. That means his is on the road crisscrossing the country at least 10 days each month. Money is not a pime consideration, since Reagan has the backing of very wealthy Repubicans in southern Califarnia.

It was one of the few times in American politcal history that a challenger from his own party sought to deny the nomination to an incumbent presient. Running against President Ford in one primary after another in 1976. Reagan at the GOP convention in Kansas City came within 117 votes of winning. The totals were Ford 1,187, Reagan 1,070.

Reagan is more serious man than ever before about the presidency, according to the shrewd advisers around him. They have convinced him that the office does not seek the man and that the idea of a draft is a friction.

You have to work for it, and that is just what Reagan and his lieutenants are doing. He will announce his candidacy next year when the congressional elections of this fall are out of the way. While that will mean his paid forum is out, with his devoted backers ready to sign their checks, it will be of small moment.

He has been pressed to come to the aid of one of his 1976 campaign advisers, Jeffrey Bell, who is running in the Republican primary in New Jersey against veteran Sen. Clifford Case, seeking, with a liberal voting record, a fifth six-year term. Reagan has refused, citing his eleventh commandment, a prohibition against any effort to unseat a sitting Republican.

That apparently does not count for sitting presidents, although in extenuation Reagan could say that Ford was appointed and never elected.

Bell is not considered a strong candidate and Case is expected to come through without much difficulty. Cynics believes that is one reason, the eleventh commandment aside, for Reagan's hands-off position.

That attitude, it has been suggested, could alienate conservatives who might turn to another hero. But that is hardly to be taken seriously, since finding a Republican to the right of Reagan with national stature and identity is like the search for the Wizard of Oz.

In a Gallup poll last November, Reagan outranked Ford 33 to 20. Other potential Republican candidates trailed far behind, with Sen Howard Baker of Tennessee closest with 8, followed by Sen, Mark Hatfield of Oregon with 3. A more recent survey puts Ford ahead by a consderable margin. While he has made a half -humorous reference to his possible candidacy, no one is sure that he intends to make a serious try to regain the office.

Name identity is no problem for Reagan. Millions saw him on television when, after his narrow defeat at Kansas City, he made an impressive reiunciation speech pledging to work for the ticket of Ford and Robert Dole. Loyalists around him are now saying that if he had begun to campaign early enough in 1975 he could have won.

Many of the same delegates who came so close to supplanting Ford will be represented at the 1980 convention. They are for the most part hard-shell Republicans who agree with Reagan's views and like his style. He has been cultivating those men and women just as Richard Nixon did in 1968, when he had the nomination locked up even before the opening gavel sounded in Miami.

Age is considered Reagan's greatest handicap. In January in 1981, if nominated and elected, he would be 70 years old. William Henry Harrison, old Tupecanoe, was the only president to be inauguarated at that age, and he died of pneumonia six weeks later. Reagan's handlers insist he is in the best of health, spurred by the pursuit of a glittering goal on the distant horizon.