[kathywithbirds]

you can do overnight for $22/$24 at the post office.

Go with a "smallish" box (less than a foot on a side), and either line it with a small styrofoam cooler (I cut some down to fit) or fill it with styrofoam peanuts. Or both. Use a small soup thermos or a kids' thermos, fill with 3/4 tank water, insert smallish frag (one per thermos is best, although with zoos they're tough buggers, can do a couple per thermos -- the rocks they're mounted on clap together and can damage the frags). Baggie the thermos a few times, they're not waterproof no matter what the tag says, insert dollar store handwarmer or two (Kmart, hunting section), seal box, get to the post office before 4 p.m.