It's bad enough with glass fish, why do they have to do this sh*t to my favorite fish?!?!
Please don't buy blue or "blueberry" oscars. These fish have been artificially dyed. The color will fade over time and look like a regular albino Oscar. That's IF the fish survive. Which I would think probable, as they are usually pretty hardy fish.
On the other hand, I strongly recommend you pick up one of the "regular" (Red, Tiger, etc.) varieties of Astronotus Ocellatus, you won't be disappointed.