hello,
sorry you were mislead, unfortunately a lot of LFS do not know how to properly ID their gars, and i can definitely sympathize as this has happened to me when ordering fishes several times. now i generally ask for a photo confirmation of the fishes (or at least from the same group) that the supplier is sending out, at least this way i can be sure i'm getting the right fish. again, sorry for your luck, and hopefully the right species will soon be available. i am awaiting photo-confirmation from at least one supplier right now, and will let you guys know what i find out.
as for ID'ing juvenile gars, people like myself and richard (polypterus) study gars quite closely and frequently get together to discuss all the species. either he or myself (i am sure there are other individuals that could help out too) can definitely ID very young gars down to genus (Lepisosteus or Atractosteus) and can usually give a well-educated guess as to what species you have, so if anything comes up, feel free to post a pic!
i also have a juvenile gar ID key that you can check out here:
http://aquaticpredators.com/forums/index.php?showtopic=2739
(mods if there is any sort of violation with the link post, feel free to remove)
hope that helps!--
--solomon