Combined cycle can be as low as $37 during low price periods of natural gas; combustion cycle is around or higher than the $70 in the podcast. Dedicated peaker plants can be much more expensive depending on the design.
Where are your numbers from? "during low price periods" doesn't really make sense here, we're talking about LCOE which is the average cost over the lifetime of a plant.
LCOE is entirely fictional unless looking at a dead plant. Anyone who claims to know what natural gas prices will be over the lifetime of a plant should be avoided at all costs.
If you want numbers, search Google and find your preferred sources. It'll take all of 10 seconds, I promise.