Sub-$15 silver are the good old days? Not by my definition.
I remember $1.29 silver, but did not aggressively act on it, partially because it was too expensive for me, and partially because my crystal ball was broken.
Think of it this way. $15 silver is one work hour where the minimum wage is $15 per hour today. When silver was $1.29 per oz, it took 1 hour and 18 minutes at the minimum wage to buy one ounce of silver. Ignoring taxes, of course. Based on that, it seems to me that silver is pretty cheap at $15 per oz.