I just updated my website with additional Harrah's prefix cards that I now have available for trade or sale if anyone is interested. All new prefixes added are marked in red so they stand out. I now have a tremendous number of different prefix cards available but I think I'm probably the last collector collecting these. If you are collecting prefixes and see anything you need please let me know.
Cards are listed on the Harrah's page on my website.
There's a link near the top of the page where I have a copy of my spreadsheet showing what prefixes I have for each issue Harrah's/Caesars card if you want to check if you have anything I need.