Voters can be allowed the benefit of additional concessions or ‘discounts’ on public services ( public transport, Bank fees, etc.).
Everyone will have to use some sort of public service in their life, these concessions will give everyone an incentive to vote. The voters can be given a choice as to which public service they want the concessions for, that particular service will be available to the voter at a subsidised rate. For example, a voter living in Delhi may be given concessions on the Metro fare.
Of course, the extent and duration of these concessions can be calculated by looking at the economics of this proposed system. But owing to the varied types of public services provided, this system can be implemented with relatively less expenditure.