You may assume quality, but you'd be wrong. Yes, these chips are all manufactured in Asia, but the design is what affects performance and quality. If you don't know the difference between CD-quality 98dB SNR (Sigmatel) and 88dB SNR (ACTS) or tell the difference between 35h battery life and 12h battery life then you may be shopping on price without understanding the concept of value. Given the dominance of the iPod, which has a much higher price than other MP3 players but offers a great user experience, I'd say that most Americans do understand real value vs. just price. Sigmatel offers better than iPod performance and features at prices that are close to ACTS.
Perhaps their biggest problem is that they have not effectively communicated the value to end consumers, who all assume that these things are commodities.