You may not get a lot for R.s 40 these days, but you will definitely get a good enough light breakfast at Hotel Aadithya right around the corner of Vilakutoon Junction at Madurai. It is a simple vegetarian restaurant that also serves good variety of tiffin dishes for the evening.
For just Rs. 40 you can have an idli, a Vada and a cup of Ghee pongal along with a choice of Mini Dosa or a Puri, top off with a mini coffee. This is a good menu for every day eaters who would prefer a simple yet economical and reliable breakfast rather than going for cheap roadside eateries. Best of all it is located right in the middle of the town at Vilakutoon Junction. It has a good pillared home style interior as well, probably converted from an old residential house.
The food itself is better than most other vegetarian places around, like the famous chain that goes by the name containing the Number 2 in between the first 2 letters of the English Alphabet, which is also located around the same place. At least the service is a bit more respectable than the mentioned chain above.
If you are in Madurai, local restaurants such as this are better places to go to than follow the famous chains and outlets from all over. They offer you many simple and tasty choices compared to the rest and Aadithya is one among that.