I'm not sure how well-supported this product has been (the website itself seems down, if that's any indicator), but https://itunes.apple.com/us/app/buy-back-you

I'm not sure how well-supported this product has been (the website itself seems down, if that's any indicator), but https://itunes.apple.com/us/app/buy-back-your-vote/id535014326?mt=8 https://itunes.apple.com/us/app/buy-back-your-vote/id5350143... was done as a project last year in one of my university courses.