In regards to the U.S. I would argue the absolute cheapest option would involve going to a fairly large community college first then transferring to the cheapest in state University.

This is a ranking vs cost issue somewhat. Ga tech is a good school in the top 5 but not as cheap as the Wyoming state schools for cost[0].

[0]: https://www.cnbc.com/2017/01/04/10-states-with-the-cheapest-...