A simple option is CrowdCurity - reward programs as a service. Private or public, dollars or bitcoin payments - everything setup and managed for the companies.
Ps: the idea is pretty cool. So is the implementation =) though how would you guys have handled if an issue like this occurs on your platform? A submitter submits a bug but the company refuses to pay for it citing "out of scope" ??
You know, you are just harming yourself this way. If you must show your stuff on HN, why not post it as a ShowHN?? why do this dishonorable thing to gain attention? IMO it actually harms you.
https://www.crowdcurity.com/
Disclosure: I'm co-founder of CrowdCurity