There really cheep to buy, like $10 for 1000. My friend gets them from a place (I think it's called Rainbow mealworm farm???) Yes they can live off of oats, but easier than that they can live in a dormant state in your refrigerator for quite a while. Chickens love them, if their getting old and you are going to order a fresh batch just find some chickens to give the old ones to them.

I'll get you the number for the mealworm farm my friend uses tonight. I know she's been using them for a long time and has been very pleased with them.