Can I pay to use lpc assets?

Can I pay to use lpc assets?

Guarav0 Has created an online version of the Universal Sprite Sheet, located at

I love this tool, and I would like to use it to generate a lots of characters in my commercial game.

(The sprites might be modified but I will release all the modified sprites I use in game, and providing the infomation and links to credit the artists.)

I know that the assets the tool includes are from many different artists.

And the assets are under CC BY-SA 3.0 and GPLv3. (though I dont really understand the protocol exactly.) 

I know that the formal way to use this assets is asking every artist for there license and waiting for their respones. But it sounds impracticable.

My question is,

is there a way that I can pay to use these character assets in my commercial game ?