How receptive has the reading public been to Don't Forget to Write and How Much Is That In Dollars? There's your answer to the potential market for this, for it is more of the same, that is to say another grab-bag of Art Buchwald's columns. He doesn't get funnier or more profound; sometimes one is forced to feel that he is running low on Ideas and originality. And then along comes a column one would not want to have missed. But let's face it; he was more entertaining reading when he was less successful. There's a note of tired creeping in. Volume three for this reader is a bit too much Buchwald. Come to him fresh and you'll probably find him a good reminder of the bles of our neighbors, a mirror held up to the American in Europe. But- unlike World's other columnist, Harry Golden, Buchwald doesn't emerge as a philosopher, a great American, someone who must be reckoned with. He's just a clever clown.