Can I buy the new DLC for Steam through elsewhere

I purchased the game through Humble Bundle a while ago, and I’d like to purchase Woman’s Lot to use with the same copy. The thing is, the new DLC doesn’t seem to be available for purchase on Humble for some reason.
Is there anywhere besides Steam (I’m not a big fan of Valve) where I can buy a usable key for my copy?

Thanks in advance for all replies

If anyone was wondering, I found the DLC on Green Man Gaming.