What is the value of a 1964 Eisenhower silver dollar?

There's no such coin. President Eisenhower was still very much alive in 1964 so his picture could not legally appear on a circulating coin. And in any case, except for the never-released minting of about 300,000 Peace dollars that year, no dollar coins of any kind were made for circulation until 1971 - and by that point they were made of copper-nickel, not silver.