We stopped at Saman's restaurant for dinner when we were in Dambulla. They serve a nice typical Sri Lankan rice and curry spread for 500Rs per person (around midrange price fo Sri Lanka; but it's way more than you can eat - includes lots of vegetable dishes - the mango curry was excellent - probably a chicken one and loads of rice, then fruit afterwards) Beer was 300Rs and a fanta was 100Rs. It was one of the better rice and curry spread we had in SL, although could have been slightly spicier (although I'm sure if you asked they could sort this out!)
The owners were very nice and chatty. They seemed to be undergoing renovation at the time, so not sure what it would be like to stay there - food was very good though!