Negotiation and bargaining.
those are the key elements for any deal you're about to make. thus it's better to have live chat with the seller, therefore Aliexpress is so far my favorite place for importing from China.
I take my time first studying the Shop itself, rating and feedback of customers, and if not then I talk Technically to the seller (most cases they know very less info about what they sell) and if they fail in technical talk I then switch to see how co-operative they are and how honestly they deal with me.
I make a good relation with the seller and thats why I go for the big shops with the great ratings and start the relation there because I will stay for long and I don't like changing every now and then between sellers at least to save myself going on and on over again about all details, etc.
what makes a relation good is that sometimes I help them, at least by understanding what they r selling and how to improve the selling based on the new info given.
here is an example for what a good relation you build could lead to:
I bought Star S7589 4GB ROM 1GB RAM 1.5GHz MT6589 SoC Quad Core Processor on 18th of April 2013 and got it on 2nd of May 2013 (some delay due to national holiday) for: $195.00 without shipping for a single piece.
no one I ever known could have reach such price for 1 piece or even 2 pieces.
Aliexpress itself would forbid the seller to put less than $197.00 for this Phone model at that time. trust me this is an Inside information plus that Aliexpress takes 5% Commission off the deal, so that means the seller is either crazy or you're a good buyer, but I would say it's actually a good seller and maybe I'm a good buyer
when it comes to buy something from China then live chat is a bless.