Wine cooler, plain ole cooler with ice packs, there's a few ways to do it. Check your fridge as well, stick a thermometer in the door for example. Some fridges are a bit warmer than others, and the door is often the warmest part of the fridge. This also works for waxworms - they don't always do well in the fridge, but if it's a "warm" fridge, they'll still be wiggly and perfect.
-Jen