Not to step on toes here or be the "controversial reefer" here but I think anemones are difficult to keep when you dont understand your tank.....and by understand I mean more along the lines of maybe have a tendency to get lazy with upkeep or havent done your research.
I bought (quite on accident) a sebae anemone a month ago and it is currently doing beautifully. I also have a BTA that is doing beautifully....my tank is only about 2 1/2 months old. I understand that my tank is young and there is a certain potential for disaster as levels can change pretty frequently with young tanks. Perhaps it is because I have gotten lucky or perhaps it was because of careful selection and planning, however after it got out of the cycle phase I never had a swing in any level again.
I would suggest if you do have your heart set on getting a anemone I would do a few things.
~I check my levels religiously and I keep a running log of the results. I always have and it helps to let me know where I am at and what I should start looking for.
~Learn about what you are getting and plan on having it for a long time. Anemones are long lived creatures and when they die, its generally because we have caused their untimely demise. Learn if you need to feed it and what, what makes it happiest etc etc
I would highly suggest a BTA for a anemone. They are pretty hardy, reasonably priced, easy to find, and if you have clownfish there is a good chance your anemone would make a good place for them should your clowns choose to park there :) The BTA hosts 16 different types of clownfish and since there only seem to be a few that we get, there is a high probability that your would be welcome. Also the movement you get from them is what is the most striking thing. My sebea is great but is NOTHING like my BTA.