These days you can prepare for CSE without incurring any huge costs. Let us just analyse how much cost you would incur without compromising on the quality of your preparation.
- Subscription of a good newspaper: Rs. 2000/- for one year
- A good internet connection: Rs. 6000/- year ( Since there are not many heavy downloads, you can go for the basic high speed plan with lower data limits.
- Print outs of some material: Lets set aside Rs. 1000 for this, which is still on the higher side
- A good prelims test series: Rs. 4000
- Mains Test Series: There are many websites that publish daily UPSC style questions based on newspaper articles. That itself should be more than enough for this.
- Model Interviews: In Delhi there are institutes like Sankalp which conduct interview sessions for a nominal amount. Rs 600/-
- Static books that you need to read: These can be obtained from a good library which would cost you around Rs. 1000/- If you plan to own these books, count in a Rs. 4000 more.
So, in all your total cost would come to around Rs. 16000–18000
Again you could cut down on many costs involved in the above. For example, you could completely rely on the online editions of newspapers, which would not cost you anything at all. I had completely switched to online edition by my third year.
You could pool in money with your friends to subscribe to a good test series. Then it should not cost you more than Rs. 400. I had done this too.
In fact, the only real expense that I had during my preparation was the money that I used to spent for my Evernote premium subscription and the internet. Everything else, I creatively cut down. For example, I read the Bipan Chandra as a library issue. Once I created my notes from it, I never referred to the original again.
You are going to enter a service where considerable amount of leadership and creativity is expected out of you. Consider this a training for that and innovate on your studies. Do let me know how you progress.
All the best.