Garter snakes arent big expo animals, I'd be suprised to see any other garters besides the ones I will have at a freinds booth.
Best time to get there is just before it opens to the public saturday morning for best picks, but the best deals are sunday afternoon when people just want to sell what they can before returning home.
They still have some red sided garters at the east bay vivarium. If you contact them they might bring one for you to pick up at the show (I highley doubt they would bring them otherwise) you can get their information here
EBV O N L I N E
It's best to call they can be a bit slow on the emails
Kevin