Food for a spanish dancer?

[cliffandtina]

My wife recently purchased a Spanish Dancer Nudibranch for me. The shop owner wasn't real clear on what its needs were. I did some research and found some info. I found that they are a difficult animal to keep and that they eat sponge. Does anyone know what exactly I should feed it, and where I may attain such a food.
Cliff

 

[bang guy]

They eat a rare Orange sponge found several miles off the coast of Greece in the Mediterranian.
Sorry, couldn't resist. Seriously though these Nidis are very specific about what they eat. There are dozens of species of "Spanish Dancers". They actually eat Tube Anemonies. Each different specie of Dancer eats a different specie of Tube Anemone.
The best way to determine the particulat Anemone they eat is to watch one eat it. Then you know. I have no idea how to maintain an adequate supply of Tube Anemone.
Guy

 

[blutang]

Are these weird looking guys dangerous to a tank? Also, how much do these things run (price wise)? I looked them up, and they look pretty cool I wouldn't get one, simply because of Bang Guy's statement above, but I'm just curious as to what they are all about.