Here's news for ethical purists who still believe that there are some things money can't buy: Embry-Riddle Aeronautical University will bestow membership on its board of trustees on anyone who donates a mere $1 million, cash.

It's no secret, and Embry-Riddle was hardly coy about the offer. The school placed a large advertisement in The Wall Street Journal offering a "limited opportunity to become a trustee of a major private university" to those "willing to invest $1 million cash (minimum)."

"We had absolutely no qualms about doing this," said Jeffrey Ledowitz, executive vice president and chancellor of the 6,000-student school, which has campuses in Daytona Beach, Fla., and Prescott, Ariz. "To tell you the truth, we're even proud of it."

He said Embry-Riddle was only stating publicly the same quid pro quo implied in donor relationships at other private universities.

He said officials of several other schools who called Embry-Riddle in response to the ad, far from being outraged, "expressed regret that they hadn't thought of it themselves," but there was some sharp criticism within the academic community.

"I never heard of anything like this," said Robert L. Gale, director of the National Association of Governing Boards of Universities and Colleges. "Our position is that an institution should carefully select the right individual for its needs. I'm sure this has never been done before, and it doesn't sound very good."

According to Ledowitz, the offer was prompted by straightforward considerations of principle and necessity. He said that Embry-Riddle supports the Reagan administration's reductions in federal student loan programs, and is seeking to build its own loan fund to aid students.

None of the money raised--if any--will be used for "brick and mortar" or for faculty salaries, he said. Ledowitz said the ad had attracted "one or two viable leads," but most calls came from the press.

Embry-Riddle, founded in 1926, offers traditional liberal arts courses, but the emphasis of its curriculum is on aviation-related studies.