Here's an idea: why not ban abusers?

I actually think games that have been in bundles and bundles shouldn't be allowed to be given away.

I know it's hardcore but who cares.

They usually are banned. Loko has been cracking down more publicly recently.

I agree a bit on this, if someone just bought the bundles for 00.01$ wouldn't that lose the gift purpose anyway? =)

Maybe some sort of proof that they paid more then 1 cent? Is that even possible? Not sure myself...

You mean we can't give out multiple humble bundles anymore? Or banning anyone who does give them out?
If we aren't allowed to give them out, why are they in the list TO BE GIVEN OUT?

The rule of giving only full (over average) bundles would be okay.

Because banning innocent users is a great way to get a bad reputation and make the site die. As you said yourself, they "most likely" only paid a penny, there's no proof they did or didn't.

Unless while we're at it, we start to ban all Dirt, Portal 2, Dead Island and Serious Sam now. (And any other key that has any sort of possible discrepancy)

ETD - That would be the easiest solution to implement and enforce.