What I thought you meant by "taste", is the sound signature of these headphones. And they're all in the same sound signature family.. so to say that one's designed for the Japanese market, well, doesn't make much sense.
Just so you know, Audio Technica don't have any official retail channel in US whatsoever, so they're not available at all, unless through specialty websites. This includes the ATH-9xx and the ATH-Axxx series.
In fact, Sony CD3000 is not officially available in US either. You can get them, but as far as Sony's concerned, it's not an official product here in US.
If you want proof of quality, here it is.. specs:
ATH-910/908:
Impedence -> 40 ohms
Maximum Input Power -> 120 mW
Frequency Response -> 20 - 22,000 Hz
Sensitivity (1 mW) -> 90 dB
ATH-A900:
Impedence -> 40 ohms
Maximum Input Power -> 2000 mW
Frequency Response -> 5 - 40,000Hz
Sensitiveity (1 mW) -> 101dB
Yes, there's your definitive quality difference. The spec of what range of sound it can generate... regardless of sound signature, something with that big of a spec difference, is *HUGE*.
In fact, ATH-910/908 has exactly the same spec, makes me think they're probably the same product with different revision. Generally they're recommended for studio work, for isolation and recording studio. They're not meant to be audiophile quality headphones.
Edit: btw, yes, they're a good deal at $25, because they're normally $50 to $60.. but they're not "good headphones" in the same way we think about Audio Technica's other products.