Notebooks are very economical than laptop only they are smaller in size. HP notebook starts from 18,000/- Rupees only with 1 year warranty. You can get great configuration, features, applications and user experience with HP notebook. There are other brands also available in same range. You can choose one of them.
If you prefer to buy only laptop then some brands as suggest above available at price near by 20,000 Rupees. But you have to adjust with configuration and specification. At this price you can get dual core processor with least 120 GB hard disk, 1GB Ram, no Graphics card, etc.
Other choice is to buy second hand good working laptop from quicker or other online shop. Many students used to sold there laptop to buy advanced one in this case you can get good deal.
Above information is as per my knowledge configuration and specification may changes with different kind of brands.
with best regards