I believe the US Mint only sells special proof coins to the public, and sells its normal gold and silver through dealers. The going price for a Silver Eagle is about $17.50 at a dealer, but the proofs from the mint website would be much more but probably retain their premium if you keep them untouched.
Proof in this context means a special mint mark, maybe W for west point, and a perfect mirror finish.
I do not buy proofs myself, but they quickly sell out every year so a lot of people like them.
