I have check on policybazaar.com for Hyundai - i20 Magna, (Price Rs.479900/-).Find following premium for IDV of Rs. 455905/-
1- Iffco-Tokio General Insurance = 11724
2- Bharti-AXA General Insurance = 12549
3- Reliance General Insurance = 14200
All the above premium are cheaper than your dealer's quote.