because you need a collection liscence to take anything from the beach or ocean, infact there are a few groups in California that patrol the beaches to prevent unauthorized collection, its for many reasons, the collection process, many people are un experienced and will damage what they collect, also many people dont know what they are collecting and often take things that wont survive in their tanks, also the whole point of this hobby is to recreate and preserve natural oceans and reefs, and unathorized collection is a serious detriment to this goal, please do not go out and take stuff, go the LFS drop the cash and buy what you want, if you are cheap and not willing to spend money then this is the wrong hobby for you...