| I own three Frios. I use one to keep my pump cool in the desert or on the beach, carry my extra insulin in another when traveling... I still have the pen sized one too. I bought them all at full price over the years, never found any discounts. They are a breathable fabric bag with sections to hold the crystals (like a down sleeping bag holds the down) which are soaked in water and cool by evaporation as the crystals let the water go. They slip into another breathable bag to keep the whole thing clean. As long as they are kept wet and have air circulation, they keep insulin cool enough, even in high heat areas.
That said, you can buy the same water-absorbing crystals at the garden store. They are clear polymer, to add to potting mix. Some people make bandannas out of them for hot days or running. You can make your own insulin cooling bag. They are also available on the internet, along with instructions for making cooling wraps, can coolers and other things using them.
Mich | 
