Precious metal value doesn't change, unless there is a big new supply suddenly made available (as in 1849 California). What appears to change the the price of silver, gold, platinum etc is the size of the ruler used to measure their price... the US dollar in most cases.

The dollar used to be worth 1 ounce of silver. Over the past hundred years, the creation of the Federal Reserve system and lack of interest by our country's leaders in keeping an honest dollar, have made the ruler smaller; it now takes over 20 US dollars to buy the same ounce of silver.

So the answer to the question of how low will silver go can only be answered when the chaos in the world monetary system settles out over the next few years. I'm comfortable saving silver (and gold) for as long as I have savings to protect. The zero interest rate edicted by the Federal Reserve can't hold forever, and when rates go back up, the ruler will start to shrink again. Eventually it will take 40 or 50 paper dollars to buy the ounce of silver. When runaway inflation begins, you can see thousands of the paper dollars required to buy an ounce of silver.

In the meantime, the value of silver remains constant; how much paper you need to buy an ounce will depend on how many people (and countries) can be fooled into thinking the dollar is a good place for their savings. Alternatives (like the Euro) are in many cases in even more trouble and that extends the life of the US dollar as a place to hold savings.