您的意思...是指...當正式銷售時...在美國的大部份商家...都是用最大的折扣來賣給
USER的...是嗎?

Not always 最大的折扣. But because of price match policies, stores will try to beat each other's price. Eg. Store A might want to sell a DVD for 19.99, but since Store B is selling it for 17.99, Store A might lower its price and eventually sell the DVD for 16.99... Usually, the lowest in-store price is somewhere around 40% off the MSRP

如果是這樣子...那可否請教一下...像網站...如 : AMAZON...在正式銷售時...以他
們以往的銷售手法...到時是否其價格也是會有到像現在預訂時的價錢呢?

Online stores, on the other hand, usually do not have price match services. Therefore, the price for pre-ordering is usually the lowest ( about 30% off MSRP) and after the DVD is released, the price will go up to 25% off MSRP or even 20% off MSRP.

That's why people in Taiwan choose to pre-order...
1. the price is usually better
2. even though pre-order prices usually are not lower than in-store prices but since people in Taiwan can not come to US and buy DVDs, pre-order prices are usually the best price they can get.