If I can buy 10 grams of silver for $8, simple math tells me that is a better deal than 1 oz at $30. Am I correct?
Verifiable 'Purity' is the key.
Correct. 10 grams for $8.00 = 80 cents per gram. One ounce for $30.00 = $1.07 per gram (which is 34% more).
How pure is the silver in each case?