Keep buying if you can = if you aren't broke from having already bought a ton of it, and assuming you can find a reputable seller that isn't trying to screw you with his premiums and bs about having paid more for it so he can't sell within a MILE of spot.
As far as how low it will go... it could go A LOT lower if this business with Russia gets real sour. The Euro has been slipping since it started, and the lower the Euro goes, the higher our beloved... HA... dollar goes. Europe and the US are getting nasty with Russia about them being balsy with the Georgians, and if they don't back down soon, we could start kicking them out of things... like the G8 among others. If that happens, they will mess with Europes oil supply lowing THEIR currency, and since we get our oil from the Saudis... we won't be affected NEARLY as much, thus making our dollar QUITE strong and silver look QUITE bad.
~Dave