I am in the UK, so I can't recommend any US sellers, but I have bought some kiloware on ebay. I have found that checking feedback is a good idea. Also, if they say there "may be some duplication" this usually means LOTS of duplication. The best seller I found has 99p starts like the rest, but his lots sell above the average - I think he has lots of returning customers (He's got me hooked, for a start!) as his lots are always interesting and good quality. Read the descriptions carefully to make sure its what you want, check the wording(for instance some use "stock" photos of a "typical" lot, others use photos of the actual lot they are selling), and go with your gut feeling. If you find a good seller, stick with them.
I just ordered and received this yesterday, I HAVE NOT OPENED IT YET so I can't say yes or no on quality and age however it seemed pretty cheap and arrived fast. He seems to have alot for sale. the feedback on this seller was 98% and 1700+ sales so I felt comfortable buying.