I’ve been to a few Indian restaurants in the area, and while I can’t vouch for their authenticity, I can say which ones I like.
Shiva’s Indian Restaurant at the corner of Castro and California is probably my favorite. For lunch (the only time I’ve been there) they have a buffet with many tasty vegetarian and meat dishes. There is also salad, fruit, and desert. Naan is included, and is usually fresh and hot. Drinks are extra. With tax and tip, this will set you back $15.
Another place I tried recently is Sue’s Indian Cuisine another block or two down Castro. Again, for lunch they do a buffet. Not as big a buffet as at Shiva’s, but tasty. I found some things that I don’t see at Shiva’s, like Idlies. The price is a couple of $ less than Shiva’s.
Flavors is at 867 E. El Camino Real in Mountain View. Their buffet also has both meat and vegetarian dishes. They don’t fill up like the other two places, and the price is even less.