Breeders come from all around to expos, just so you know what I would do to try to research the best breeders that will be at an expo is to first find their vendor list (http://www.reptilesupershow.com/vendor_list.html).
Next go through the list and see who even keeps beardies (from experience I know a couple names that are big name companies that are great for supplies, not so great for reptiles, example: LLL Reptile),
Here's the list of breeders that should have beardies at the expo:
BTM Exotics (Jay Sommers)
Phantom Dragons (Josh Dovenbarger)
Greathouse Farms
Ron's Reptiles (possible flipper)
Southbay Tropicals and Reptiles (possible flipper)
Inland Bearded Dragons
Just so you are aware when I put possible flipper it was because they seem to have a little of everything, not always a flipper (someone who buy and sells, buys and sells), but something to look out for since they don't always have the best quality animals. I feel it's always best to find someone who specializing in just a few species rather than has a little of everything.
Now that we have a list, we need to research each breeder, when searching the main thing to look for is bad reviews and see what happened (I use Fauna's BOI):
BTM Exotics (Jay Sommers)
http://www.faunaclassifieds.com/forums/showthread.php?t=166061
Phantom Dragons (Josh Dovenbarger)
http://www.faunaclassifieds.com/forums/showthread.php?t=185546
Greathouse Farms
(couldn't find a review)
Ron's Reptiles (possible flipper)
http://www.faunaclassifieds.com/forums/showthread.php?t=165991&highlight=Ron%27s+Reptiles
Southbay Tropicals and Reptiles (possible flipper)
(couldn't find a review)
Inland Bearded Dragons
(couldn't find a review)
So from what I can see on the websites and on BOI, I would reccommend BTM Exotics, Phantom Dragons, or
Inland Bearded Dragons. Even though I could not find a review for Inland looking over their website I would say they look like someone I would deal with if I were looking for a dragon. Now will any of these guys have what you want? That's a different story, you could contact them and inform them what you are looking for and see who might have what you want at the expo. If no one does there are several breeders around the country you can buy from and they will ship them right to your door.
Hope this helps a little.