David Moyes signed Baines for the Toffees from Wigan for £6million in 2007 with Fellaini arriving from Standard Liege for £15million the following year.
United's offer for them is believed to break down as £12million for Baines and £16million for Fellaini.
Martinez does not believe Moyes would have considered selling them for such a price.
He said: "As a new manager, I am following the structure we have at the football club. I heard in the past that Everton never sold cheap."
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