alibaba.com
They are a chinese site some prices seem to good to be true.
Yes but it depends on the vendor from the site.
Just a b2b meeting place, full of independent manufacturers or more often exporters. The prices are sometimes good, but you'll need to convince them to sell you an item as a "sample" in the hopes that your "business" will buy in quantity. Each sale carries it's own risk, alibaba has little to no control after setting up the blind date.
Some of the GPU prices if you look around are very good ( they do want big volumes though like you said convince them for a sample ) , I came across some ram and CPU's as well for some reason Intel seems much easier to get.
As example of some prices GPU 7950 $100 7970 $115 7990 $275 GTX760 $137 GTX780 $230 I5-3570k $95 I7-4770k $170
I also noticed some vendors charging top dollor so it's a bit hit and miss by the look of it.
I think it would have to cheap to off set the risk involved.
I have no idea of shipping costs that may be a killer.