Just an opinion, but I would'nt bother with ebay.

It does have the shape of a hollow scraper, and you do say the edges
are very sharp. Yet the type of stone(in my opinion) is not in keeping
with scrapers.

Hold on to it and ask someone that is up on such things to give you
some idea.

I would be more intrested as to the goings on at the place in which you
found this, was it animal activity or could it be human activity?