its all about their distribution centers & fulfillment centers.
http://www.mwpvl.com/html/amazon_com.htmlIm a prime user too - doesnt take many purchases to justify the cost of a prime membership.
prior to being prime members we RARELY paid for express shipping (didn't matter who we bought from)...but we still got hit w/ shipping charges, as Amazon Prime member we (largely) avoid shipping charges and get it faster TOO.
I have noticed that where Amazon used to beat everyones price, it seem their prices are creeping up - i still give the advantage to amazon - even if the price is the same, we usually save on the shipping & get it in 2 days.