This is an authentic pure vegetarian jay restaurant offering buffet style meals with lots of vegan 'meat' choices and the food is absolutely delicious. When we went it was rice with 1 dish for 40 baht, 2 dishes 45 baht and 3 dishes for 50 baht, so quite standard prices for jay restaurants (read my vegan in Thailand travel tip!).
The owner doesn't speak English and it might have been miscommunication, but be aware that "flashier" dishes in the buffet might not fall under the same price structure. This, we learnt later, is quite common in jay restaurants, but we didn't know it at the time and tried a vegan fish that was amongst the buffet dishes, only to discover upon paying that apparently the vegan fish had been 35 baht extra each. The owner had made no attempts at informing us about this so it left a bit of a sour taste in our mouths.
However, if you go and just ask what falls under the buffet structure you will be completely fine. The food is so good so it's definitely still worth the visit!