The 1964-P Roosevelt Dime is very common in most grades and can be purchased close to its metal content value. Only examples in MS65 and higher usually command some sort of a premium well above there metal content. Examples in MS65 and MS66 condition, although somewhat scarce can still be purchased at a reasonable price where just about anyone can afford one. Only in MS67 does it become very scarce where the price is significantly high.
There are probably several hundred examples that exist in MS67 with very few known or possibly known at all any higher condition. In MS67 FB it is much scarcer with less than 50 examples known and none being in any higher condition.