for new books I go to RIBA books but then I'm not in the US either but they ship anywhere in the world

it's not specific to architecture, but i like to use
fetchbook.com, it's an aggregate search site of other book sites.

If they are in good condition and interesting email me

I have a market place in Amazon. and it is ridiculous that they only give me 3.99$ for shipping. I just mailed one book, the superstudio to a Newyorker, and I payed 6.99$ for shipping price. It cost me 3.99$ more of shipping, and the only way to handle this is to increase your selling price in Amazon which probably exceeds the origional price as a new book. And amazon would charge me 20% for the total price. i just do not get it. So if anybody want my books, email me and I would give you a list of the book.

or you go to amazon seller, search "Xingman".

Not sure about selling, but for buying you can't beat Prairie Avenue Bookstore in Chicago or Powell's Books in Portland.

The best-kept secret among bibliophiles, architecture or not:

www.bookfinder.com

I am sorry you guys could not find my booklists on Amazon since the search tool is cracked.

Here is the link, and please do not purchase them from Amazon as the shipping price is an issue for me (like S,M,L,XL is too heavy to ship with only 6.99$), always send me an email and we could talk about it.

Address: http://www.amazon.com/gp/shops/index.html?ie=UTF8&sellerID=A2QNM0WL6ANCJZ

The very best for the very best.