In your Contest Category settings you can choose if you wish to enable the Buy Votes option, set the cost, and choose if you want to use PayPal and/or Stripe. As of version 1.5, we have added tiered voting pricing. So you can now set an amount per votes with a range like $1 for 4 votes, or tiered pricing such as $1 per vote for 1-5 votes, .75 per vote for 6-10 votes. You can add unlimited tiers.