I've written before about the cost of an obit in my hometown rag, the Columbus Dispatch; a year ago it charged $5.73 per line per day, $8.21 on Sundays. Count the number of lines in an obit and you'll be surprised at the price tag.
Legacy.com has become the dominant memorial site as it partners with newspapers so they can bundle print obituary/memorial information with online content. It claims to work with 124 of the top 150 newspapers in the country, and draws 14 million readers a month. Legacy.com memorials are free for 14 days, but to keep them live after that point requires buying a sponsorship at $49 for the first year, $19 per year thereafter.
Another major online memorial site is Tributes.com, started by the founder of Monster.com. Here, too, a tribute is free for 14 days. The cost thereafter is $299 to have it remain live in perpetuity ($249 with a military discount). It recently announced that it has signed up to 50 television and radio stations that are attempting to stake a claim in the memorial business via their Web sites. (Yeah, that's where I'd like to be memorialized --- right between the ads for Cialis and the Slanket.)
Like many other Web sites, Tributes.com requires visitors to sign up in order to leave comments, so you can expect your information to be sold to those firms targeting your demographic shared with firms that partner with Tributes.
(Clarification, 12/8: Tribute does not require visitors to register, but does require name and email address before allowing them to post a memory to the memory book of a tribute. The company assures me that these are not retained or passed along.
Those that do register in order to create a tribute must agree that Tribute may "provide the information to trusted partners who work on behalf of or with Tributes under confidentiality agreements. These companies may use your personal information to help Tributes communicate with you about offers from Tributes and our marketing partners. However, these companies do not have any independent right to share this information.")
One of my fellow writers describes the new competitor Memorypool.com as Facebook for dead people, a rather apt term. Like Facebook, it is free, and the architecture seems very similar. It states in its policy that it will not share your information with a third party.
In the national shift from print to online media, fewer and fewer people will be coming online via the newspaper gate, which is the greatest strength of Legacy.com. Like it or not, the going price for online information continues to be zero, and those sites attempting to find a middle ground of profitability between zero and print obits are probably going to find it hard going when faced with competition such as Memorypool.com.