Why should you be checking the seller and the item
? Do you really need to ask this? There are thousands of sellers out there and some of them are scammers, selling look alike products and caring little after the sale. You need to be verifying the authenticity of the item as well as checking out the sellers history. Dont be scammed and lose your hard earned cash. Do the research and buy something real.
To do effective research on the item you are buying you can use an effective combination of a good reference librarian and a broad internet search. If you do this right you will be able to find out the exact name and location of the manufacturer and with this you can further broaden the search on the internet and/or the library. You will want to learn all you can about the company and the piece.
Starting with the manufacturers name is a great first step. This can open up a lot of leads which will provide further information that can be found on the internet as well as the actual manufacturer itself.
The products manufacturer will help you understand the production history and enables you to begin discussions with the seller about the product. Ask him the questions you need to cross check against what you have discovered. Keep repeating this until you feel confident. And dont forget to view the item in person. Photo's can be faked.
Now you have answers from the seller. You have information to cross reference against your research. But you still need to check the seller out. Learn what you can about his reputation, check out previous feedback in Ebay etc. Be comfortable with the seller before you proceed to buying or visual inspection. You can also refer to good web sites with more tips and links.