Never buy livestock based on what the store says. Many will put the sale above what is best for your tank or the animal. Always research when something should be added to a tank, whether it is compatible with what is already in your tank and if it is compatible with the things you plan to add to your tank down the road.
I know it can seem that anemones and corals are more plant like than animal, but they are animals. Do not buy them unless you have done the research and KNOW you can meet their needs. Buying coral, nems, or even fish, for that matter, without knowing your tank is stable enough and your lighting is intense enough for that animal is no different than buying a puppy and not being able to care for it properly and watching it slowly die.