Quite a few people talk up Beyond India, and they're alright, but honestly if you haven't gone to Indian Temptations on Main North Road (just a km or so south of Gepps Cross), you need to do yourself a favour and go there. The place looks like an absolute dump but you will never taste better Indian food in your life.
The only problem with it is that it's pretty much ruined every other Indian restaurant for me now, because every time I eat Indian food I just find myself thinking "I wish I was at Indian Temptations instead."
Pretty cheap too and it's open to something ridiculous like 4AM.