What is the best way to obtaion a dragonstone in runescape?

I got this directly from tip.it "The members only Dragonstone gem is obtainable from the Crystal chest in Taverly. This chest is located in the house south of the main road (south of the witch's house). To open this chest you must have the Crystal key. This key is combined from the 'teeth half' and the 'loop half' keys, which are both rare drops from many monsters."

You can buy the key or the two halves for 82K.