Hipstamp was started by the same guy who started bidStart. It is quite legitimate. I have bought several items from sellers there.
sellers also have stores at HipStamp.
I do find the descriptions on eBay
to be generally superior to those on Hipstamp, especially for the same item being offered both places. Hipstamp sellers also seem less inclined to publish their policies on extensions for certification. This MAY be due to spatial limitations in the listing software.