I buy my cricks from Ghann's, but I keep check of the weather forcast, and wait for a relativly warm day (they do happen!) and pick that day for delivery.
I once ordered 1500 last winter, delivery day was below 30F, and I was not home, so box had to sit outside for 2 hours.
Needless to say, they were all dead!!
From now on, I check the weather, and plan to be home on the day of delivery.
Dont rely on the heat packs. When it's really cold, they dont help much.
I am having success with breeding the brown banded cricks, and have thousands of babies, but they take forever to grow up, and a rotation schedule needs to be planed so I always have the right size (easier said then done!!).