I know this is an old thread, but after ordering fish online, and watching FEDEX botch an overnight delivery, in my opinion, you can do better by driving to Cheyenne or Fort Collins. When FEDEX botched the delivery, I ended up with dead fish. The overnight delivery charges would easily pay for most of my gas.
I have transferred my 55 gal. tank and all the fish two days cross country using an ice chest. It worked out fine. All my plants made it, including my Madagascar Lace, algae, snails, and most of the fish. So, it can be done.
If I ever use FEDEX to transport fish again, I will make sure I'm at the local airport to intercept the delivery. FEDEX service out here in Casper, WY depends a lot on how good the drivers are (like, did they come to work today?).
55 GAL of well water, plants, and fish