I also brought home three chicks around the same age yesterday, and my story is exactly like yours. They peeped part of the way home, then got quiet and just slept together when I got them home and through the evening. They weren't interested in the food and water, even after I dipped their beaks in them. Today, though, they finally ate the food and were drinking water and moving around a little. I think the change was just a little scary for them, since they had been with about 50 other chicks where I had gotten them.
Just keep an eye on yours and check the level of the food and water.