Follow urtheman's suggestion - there many great restaurants and bars just outside the resort area - all priced lower than the hotels in the resorts complex.
But, since you asked, drinks (cocktails) at the hotels will start about B100-120 (happy hour) and go up from there.
Up and down the beach - just outside your hotel are lots of excellent "beach shack" type restaurants where you can eat with your toes in the sand.
Lotus - mentioned above - is my favorite! Here is a webpage about Lotus:
http://phuketdelight.com/Lotus.htm
The Lotus will be north of LBR about 1/2km - right on the beach - can't miss it.
Just outside LBR - is also a nice beach restaurant called Tom Yam Goong - also excellent. Farther to the south - just south of Rydges/Amora - is Bang Tao Seafood - also super good.