The 1964-D was struck at Denver but actually has a higher mintage than ones struck in Philadelphia. It had a mintage of 704,135,528 and the one struck at the Philly mint had a mintage of 560,390,585. Neither coin has an added collector value in circulated grades and in low mint state grades (condition). The value depends of the price of silver which changes daily. A coin that is uncirculated has no wear. Make sure the coin has all the fine details , look at eagles wings to make sure all feathers show with full detail. Washington's hair must be sharp and noe missing.
51 years a numismatist, Red Book a Guide to US Coins, Coin Dealers Newsletter