(MONEY Magazine) – Although I have no quarrel with most of the suggestions contained in your December feature ''How to Cut Expenses by 20%,'' I do object to the blanket recommendation to send children to public colleges and universities rather than to private schools. My perspective comes from being president of Bucknell University (a private liberal arts college with 3,350 students) and the former dean of the College of Arts and Sciences at Indiana University (a public institution with 90,000 students). Discount shopping may make sense when buying toasters, but it could prove costly when it comes to a college education. The key is matching a college with a student's preparation, maturity, ability, aspirations, expectations and goals. If the match isn't right, the lower-priced school may be no bargain. Gary A. Sojka Lewisburg, Pa.