Oh, I wanted to address the concerns regarding the Navy. They are quite valid, and I wanted to add some information that may make it easier to accept getting them for the Repo cruise.
The certificates put out by Tiffany Publishing are not awards or recognition officially used by the Navy. They are primarily momentos of certain events that may be important for a sailor, and are used by a ship's Captain to maintain positive morale. They are not required, however.
For instance, there are several certificates on their website that I should have received, but the ship decided not to participate. The Suez Canal transit and crossing the international date line (the order of the dragon, I think) are two off the top of my head that I never got and do not have in my service record. There is no certificate for my first shellback award, but it is logged in an obscure place, so I didn't have to get hammered the second time around. I did get the certificate for the second event, though.
The funds for the certificates are not provided by the Navy, but the ship's own Morale, Welfare, and Rec fund (money collected from the sailors onboard via soda and store profits as well as other events). Thus, the Navy does nto have any concerns with the certificates, and promote their use, but do not officially buy them.
The main reason the versions shown have Navy ships and seals on them is simply because the Navy is the largest customer for Tiffany. As was mentioned, they are happy to do special orders, especially if it is int he hundreds (like the numbers on the repo cruise for the DISer meet). The shellback ceremony dates way back before the inception of our navy and was a ceremony for mechant sailors to provide entertainment and as a right of passage for newbies.
All in all, I do not see it as direspectful for civilians to get the certificates for trnasiting the canal. They can be altered for you, if that makes you more comfortable. I am wary, however, to suggest getting the shellback certificate, since that does have significant and personal meaning to not only the Navy, but every true sailor. There is an actual ceremony attached to this recognition, that by tradition must be adhered to. A good description can be found at:
http://www.members.global2000.net/~macminn/Shellback/Shellback.html
Transiting the canal, however, was just another day on the vessel, and thus the certificate indicates an event (liek the Repo cruise) more than a guarded tradition.