I went to the craft store and got a box of flower drying crystals. This is perhaps the cheapest way to get silica gel. Six pounds of it cost me under $20. I pour the silica in an oven-safe pie dish (aluminum or Pyrex), because it spreads the silica out over a larger surface area. I then place the dish with the silica in my safe to keep it nice and dry. When I notice the indicator in the silica gel turning from blue to pink, I recharge the silica by simply popping the dish in my oven. The indicator in the gel is more heat sensitive than the silica itself, so I keep the temperature relatively low. To recharge it, I usually bake my silica at 275 degrees Fahrenheit for two hours. As I'm letting the dish with the silica cool after it's been recharged in the oven, I put plastic wrap over the dish so the silica doesn't pick up moisture from the ambient air before I place it back in my safe. How often you have to recharge your silica will depend on the humidity in the air, how airtight the seal on your safe is, and how often you open it.