That makes sense that Better Imaging had slide film, since that's what they process at that location. Besides, you really should try slide film. It's addicting.
As for Camera Corner, the best way to find out if they have something is to pick up the phone and call them. They don't have any film listed on the web site but last time I was there they did have a few rolls in the fridge behind the counter. They never seem to have very much in at a time, but it's always fresh stock.