What Do You Buy for a Billionaire?

EXCLUSIVE

Donald Trump presented a dilemma of the highest order to his famous friends ... how much do you spend on the second wedding of an insanely rich man?

Mariah Carey, Howard Stern and Kathie Lee Gifford are among the celebs who signed the 1993 Tiffany & Co. gift registry for Donald and Marla Maples' nuptials.

Here are the highlights:

-- Mariah and Tommy Mottola ... $610 decanter

-- Monica Seles ... $540 pitcher

-- Howard Stern ... $530 crystal sail sculpture

-- Hugh Hefner's daughter, Christie ... $400 wine cooler

-- Kathie and Frank Lee Gifford ... $300 serving platter

-- The most lavish gift ... Don King ... $1,250 for a bowl