I definitely wouldn't be willing to risk 800 clams on this - I think it's exactly what the seller says it is (other than having what looks like a cedar top) but just because it's what the seller says it is doesn't make it necessarily worth anything.
It was clearly built as a ukulele, though unless someone went to the trouble not only to add two bridge pins but to remove all evidence of holes from where those pins would have been on a guitar. In fact, they would have had to fabricate a whole new bridge, basically, because six pins on a guitar would almost certainly have been installed in a straight line in the wider part of the bridge closest to the saddle. Also, they would have had to fill the 9th fret marker and put in a 10th fret marker.
It does, however, look very much like a ukulele built by someone who made guitars, and quite possibly using their guitar molds/jigs/what have you with little modification (note the width of the bridge, the width of the sound hole, angling of the bridge saddle,m etc.). It was someone, however, who knew enough about ukulele to know about marking the 10th instead of 9th fret...
John