What connection are you currently using???
- Check with your neighbours ... they might be willing to share the connection for around Rs. 500/-- ... a router supporting Guest Wifi SSID + Bandwidth limits + QoS would help in sharing the connection "fairly" ... you can manage without it of course!
- Shared LAN or local cable connections also might be in budget if available for your area
- If you have a smartphone ... you can use the 3G as a backup ... and depending upon your phone/OS, can also share it via portable hotspot! I find that the Rs. 6 (inclusive of Tax with 500MB limit) Telenor's data package for 1 hour serves as a good backup option when needed any time of the day. You'll have to activate it though every time needed and after every hour but you'll only be charged for hours you want to use.
- There are also prepaid Monthly 3G packages available from all operators that can serve as a backup! Works well if you have a router or other device with 3G/4G USB Dongle support and auto-switchover in case of failure of primary connection ... I have a TG582n router that supports such functionality with later firmware versions! This shall work with the smartphone just as well! Just be conscious of the data caps!
Hope this helps!