You can go with Living Sea coral inserts, Big Al's sells them and they ARE expensive. Just make sure you use less light over them as they will get covered in algae and scrubing them is no easy chore.
I have recently set-up a tank for a client the uses a mix of both living sea inserts and live rock. IMO, this works better as the liverock contributes to the overall health of the tank and outcompetes most of the algae for nutrients as it is also covered with macroalgae. Therefore the fake coral looks better, longer.
Another option is to use liverock and throw in a few seafans and such as I did in our 110gallon:
http://www.riftnreef.com/110gal.html
HTH
