The complete works is probably good as Nate's Autographs sell authentic stuff (although they usually are overpriced). I wouldn't touch ANYTHING on ioffer.com -- they are even worse than Craig's List.
The rareandsigned item you posted as a status is also fake. Please try to post all your questions and photos in your discussions and not as a status. Its easier to respond to. Rareandsigned only sells fake Freddie items. Best
Not really. There's no 100% solid site for Queen graphs. You just have to keep your eyes peeled. Ebay does get genuine pieces from time to time. But it's very much a mixed bag. The sites that absolutely never have genuine items are ioffer and rareandisgned. Best