Deborah's advice is spot on.

I understand you have limitations because they belong to the store, but is it a possibility that you could take them home while they are so fragile? If they are just being kept in a back room of the store, it shouldn't make any difference, right ?

If you could take them home you could probably have the perfect temperatures without any lights. I know stores can get pretty cold at night.

Also, at home you could easily and cheaply separate them. You could use little tubs. 4 small tubs that you either burn air holes into, or cut out a piece of the lid or front of the tub and hotglue some screen over the opening, so you get good airflow. That would also hold humidity well, while allowing it to dry out a bit. Water and food dishes can be free, simple bottle caps. For hiding you can use paper towel roll pieces , small cork or even a piece of egg crate.

It would end up costing very little.

That is IF they would let you do that..

I have heard that that T-Rex was just relabeled Repashy complete crested gecko diet. If that is so, then that should be fine as food. As long as it is a complete diet (mix a smoothie) and not the hard or jelly pieces. I would leave food available always PLUS do the syringe feeding.

They must be SO tiny..