Cheapest Source of x86 Cores?

I'm doing embarrassingly parallel simulations (think Monte Carlo runs of a legacy scientific binary) and am trying to find the cheapest possible host source of x86 compute, at scale. These are jobs that are single-threaded, use maybe 2-4GB of ram, last an hour, and can be checkpointed if necessary. A c5.18xlarge on AWS has 36 physical (real) cores and on the spot market is $0.74/hr which works out to $0.02/core-hour. Does anyone know of cheaper options?