Lol I think, although it'd be quite mean and greedy, you can buy it for $0. I don't have a valid credit card or anything of that sort at the moment, so I can't check. But it did seem to allow me to get through to the purchase window when entering $0. But it gave me a sad image of an indie developer begging for money on the streets in a box or something along those lines...
I can't get the image again because apparently, one of the sites that this humblebundle.com requires, olark.com, has a script that slows my browser down to a hault. I had to stop the script and now the form isn't working correctly.
