Ah, best of luck to you. Still finishing school myself, but I'll be spending most of my time interning since my course load is light.
For a con this size, we should see at least one Revy running around. The other characters are considerably less common, unfortunately. Actually, for Anime Boston 2010, our Black Lagoon group grabbed a random lolita, gave her a shotgun, and asked her to pose for us as Roberta. XD
For the most part, most Black Lagoon cosplays can be put together relatively quickly and cheaply. So, for those of you who are checking out this thread, like the series, and have an empty slot in your cosplay schedule, I welcome you to join us.
Personally, I'd really like to see Sawyer the Cleaner, the Hansel and Gretel twins, and, well, Balalaika.