Hi fatheadminnow
Here's some pictures that might help. The first is packed in Kordon Breather Bags (which I don't particularly like for corys.)
http
/www.fishforums.net/index.php?/topic/327153-new-corys-arrived-today/
Here's another thread, an older one but it might be useful.
http
/www.fishforums.net/index.php?showtopic=158249&st=0&p=1311128&fromsearch=1&#entry1311128
Here's a link to a good site to buy shipping supplies and other things:
http
/www.kensfish.com/shippingsupplie.html
If your customer will pay for UPS or FedEx overnight shipping, so much the better. It's usually reliable but it is expensive. The seller usually guarantees live delivery and will replace them but not cover the cost of a second shipment. If Priority mail is the only option, be aware that it's risky. I just received a shipment yesterday (Monday) that was mailed from PA last Tuesday. It actually went off the tracking twice. No one at the post offices I called had any idea where they were during those times. Amazingly, the corys came through it fine, but I didn't expect it to turn out that way.
I've never shipped out fish so I can only be of help from a buyer's perspective. There is a forum on AquaBid that might be a place where you could get more information if necessary. The sellers seem like a helpful bunch.