why investors are buying silver ..., page-9

Guys can someone tell me how much i should get for the original 50cent coin minted back in 1966 as it was 99.% something pure.
As silver is close to $50 i went to a coin store in Melbourne CBD and the price for one silver coin $11.50 to sell.
I do expect the dealer to make a profit margin but not 75% just to buy from me and re-sell. Why the big gap between buy and sell!!.