The sale is for the core rulebook and a set of one-off campaigns. If you beat the average, at least four other books from the system are included (more may be added as the sale progresses).
The sale is here:
http://bundleofholding.com/index/current
Unknown Armies overview
Unknown Armies homepage
The sale is here:
http://bundleofholding.com/index/current
Unknown Armies overview
Unknown Armies homepage