The flights itself are gonna cost you 10k-12k if you travelling from South....the fare would be low from Bangalore and Chennai.....and would cost around 15-17k if you are from North... And the expenses in Sri Lanka would surely cross 10k... So you need to have at least 20-30k.....
If you are talking about land yes very much possible but you have to restrict your trip to Colombo and Kandy .
Flight itself will Cost you around 15-20K return.