Here you can purchase bundles that include ranks, keys and money.
This bundle includes:
God Rank Paper
20 rare keys, 22 legend keys, 18 mystical keys and $700,000 in-game money,
Reaper Rank Paper (can be sold if you have reaper rank or higher)
10 rare keys, 5 legend keys, 2 mystical keys and $90,000 in game money.
Ghoul Rank Paper (can be sold if you have ghoul rank or higher)
4 rare keys, and $15,000 in game money.