As far as I know, the best silver to buy as investment or survival coins are Silver American Eagles or pre-1965 90% silver dimes, quarters, and half dollars. This article gives a pretty good description of what kind of currency you would want in a total financial meltdown. There is also a service I found called SmartSilver that will send you a chosen amount’s worth of pre-1965 90% silver coins every month. (I have not used this service, so this is not an endorsement. For informational purposes only.)

Since BrianTexas mentioned buying his silver an ounce at a time, I would think he is referring to the Silver American Eagles or something very similar.