The timing's not so hot for this latest gathering of Buchwaldiana: Ronald Reagan doesn't appear till the book's second half, and he only starts getting major attention in the final pages. So a lot of these columns traffic in foibles of the Carter administration--and other near-forgotten topical material of the ancient 1978-80 period (gas-lines, gold prices, the Susan B. Anthony dollar). Still, some things are forever. Inflation, for instance--as when Art shops for an anniversary present at the fruit store: ""Consider this diamond-shaped pear an investment,"" says the fruit merchant from behind his Louis XIV desk. ""In three days when it's ripe it will be worth three times what you paid for it."" Or nofrills air fares: ""the discount passengers will be loaded on board in leg irons. . . . Each passenger will be offered a choice of coffee, tea, or milk. If he doesn't guess the right one, he will be hung by his thumbs from the luggage rack."" Equally timeless: musings on taxes, doctors, real estate--and, in one of the few Buchwald pieces where his preaching jibes perfectly with his comedy, gun control. (The spokesman for the National Hydrogen Bomb Association: ""Hydrogen bombs don't kill people--people kill people."") Away from politics, Buchwald can seem merely a pale, male Bombeck--but he does nicely with lampoons of Washington novels, kiss-and-tell memoirists, or award-show speeches (""To my director Gary Ack, who doesn't know one end of the camera from the other, I advise you to go back into your father's slipcover business""). And when Ronald Reagan appears on the scene, one can positively feel the Buchwald energy-level rising: the campaign blunders, Nancy's fashion-setting, the Moral Majority--all sides of the New Washington are prime Art-istic fodder. Buchwald can laugh at anything and everything--even (in dubious taste) the failed Iran-rescue mission; only the Reagan assassination-attempt finds him at a loss for jokes. So, even if about half of this potpourri is already surprisingly dated, the sheer quantity of Buchwald's good-natured, inventive, modestly pointed output remains awesome--and the broad, bull--in readership will not be disappointed.