http://www.ebay.com/itm/Rare-BIOSHOC...-/391038621431
There's an old Ebay auction above that had a signed 16/110, and I have seen others that have the circular base autographed but without a number.
EDIT: THat link above is missing the pics, but if you Google it you can find the pic of #16
EDIT: Also found #20 on Ebay, signed and autographed
http://www.ebay.com/itm/Very-Rare-Si...p2047675.l2557