I think most Columbo fans admire the painting of the lieutenant done by the killer in "Murder: A Self Portrait", but -- $500.00 for a signed print? Anyway, you may enjoy checking it out. And to be fair, you can buy it unframed for only... $300.00. The real-life artist, Jerry Gebr, also offers the other paintings seen in the episode:
http://www.gebrart.com/COLUMBO.html
Mr Gebr has done some other interesting paintings for TV and movies. I wrote to him years ago, asking about what happened to the original Columbo protrait, but he never wrote back. Maybe the answer was that he was saving it for the day he could take a high-quality photograph for prints.