wefts

Aren't seamless wefts the kind with clear adhesive along the top, that you use for extensions? If so, you want different wefts for clip-ins- normal machine-made or hand-made (machine made are cheaper but bulkier, handmade are more expensive but less bulky).

That kind of hair can be got almost anywhere and at any price range, from virgin hair imported from India to cheapo cuticle-stripped stuff sold at your corner beauty supply store. It all depends on your price range and how high-quality you want them to be. A good way to learn about good brands of hair is to read all the threads here about human hair (almost any hair vendor sells wefts that you can make into clip-ins), and see which brands people have good things to say about.

-Rae