What is the value of an Ted Williams 2000 Massachusetts quarter?

The Mint never issued such a coin. The Massachusetts state quarter features the state outline and a picture of a Minuteman.

What you have is a privately-issued commemorative item. Unfortunately there's almost no secondary market for them. You might be able to find a baseball memorabilia dealer or collectors' website where someone would be willing to pay a few bucks for it, that's about all.