The 1994-D Uncirculated Kennedy Half Dollars are very common as the mint struck over 23 million examples. Circulated examples can be found in banks or in commerce. Higher grade examples in about MS66 or higher are much more difficult to find but enough examples exist that they can be purchased at a small premium. In MS67 condition it is very difficult to find. In MS68 condition or higher it is very scarce and any example in this condition or higher should definitely be graded.