This mod allows you to adjust cost of infinite technologies to your liking. By default it keeps vanilla scaling for first few levels and after that it lessens ramp-up. You can either set those costs to flat value or set your own scaling.

For more information about setting your own scaling you can check this website: https://lua-api.factorio.com/latest/types/MathExpression.html

This mod may be incompatible with some mods that change research cost of technologies.