Are you sure it's Imperial German? I have never seen an issued Imperial German weapon of any kind without at least inspector's stamps. I have seen exactly one genuine Imperial German lance, it was marked with the maker's name, proofed and dated, just like every other Imperial German issue edged weapon. It was priced at $1200 or so a couple of years ago. If I recall correctly, it may have had unit markings as well. I almost pulled the trigger on it just because I had never seen one. I've seen lots of German made South American contract pieces though. In the end, I couldn't overcome my distaste for horses, so I passed on it.
Steve