We used a third party payment processor for this reason. We also let people tweet their order number: https://twitter.com/i/#!/search/backer%20number%20lockitro

We used a third party payment processor for this reason. We also let people tweet their order number: https://twitter.com/i/#!/search/backer%20number%20lockitron https://twitter.com/i/#!/search/backer%20number%20lockitron