Hi all,
just want to contribute a little in this forum of what I've found.
Beside all those major online bookstore and the giant anime specialty stores.
I recently encountered this site that specialize in manga books (domestic one that is)
www.justmanga.com
I found them in google when i was looking for place to buy the berserk manga (vol 2, yeah!). their price on manga books are the best I've seen and shipping fee is quite reasonable.
I ordered couple of books just now and get their free shipping deal. will let all of you know how it goes.