I would never buy a 100oz silver bar. Fakes of them exist, and if I want to resell I would need to first find someone wanting to buy $1500 worth of silver and then prove that it is not a fake.
Much better to get a mix of 1oz rounds and coins and maybe a few 10oz bars. While fakes exist of 1oz coins too, the incentive to do so is very small and people can sacrifice one to test with acid or just cut them with hedge clippers.
