I'm surprised there isn't a bulk database available from the FDA or USDA. http://ndb.nal.usda.gov/ is in the public domain and looks like a good start. Do you know of all of its entries are in the Open Food Facts database?
I need to look again but I believe it contains mostly "average" generic products, not branded products. And no images of the product and its packaging unfortunately. Also there are no barcodes for the branded products. e.g. http://ndb.nal.usda.gov/ndb/foods/show/2072
But definitely worth another look, thanks!