Same as Hiraa..used 4 found two good ones and two total frauds.
Check the Rankings as sugested, dont go for 'really' low costings at first but of course make sure your covering things. They are just as cautious about you as you are about them! So do some good business, stick regular orders in and then work the costs down with them.
The escrow service you can use with them is very good...saved me for sure!
Also be very aware that the product descriptions are often NOT the reality esp with tech items and high turnover lower cost items,
also be very aware that some of the items are excellent copies but still not the real thing...do your research well on the real product ok.
Good Luck.