At what point does it become more sensible to black hat these zero days? If the company you are helping out isn't willing to give you more than the finger for your help it seems like you're the fool in that arrangement.
Pretty much never unless you live in a jurisdiction that won't punish you or send you to the appropriate people to be punished. If you're Russian and want to never step foot out of Russia and only attack American systems, you can do it.
Feeling grumpy today, I guess.