Thanks for the suggestion. I agree it would be an useful option but I don't think it's an urgently needed change or should be default. Space Age has its own research productivity so if you want to play with research productivity but don't like the way this mod approaches it, you could just play without the mod and use the Space Age research. Or voluntarily don't reserarch any level that you feel is too cheap.
It will be included as an optional setting the next time I update this mod but I can't promise any time for that, could be months or even years.
This mod also uses the MIT license so you can change it yourself if you want to. I won't update it without a check that disables that behavior if space age is not loaded or the user didn't enable it in the option but if you don't need that check, it should be nothing more than a small extension of line 73 (if you play with exponential cost increase) or line 94 (if you play with linear cost increase) in /prototypes/technology/lab-product.lua - just add any science pack with its quantity to the list. The line numbers are from version 1.1.2 of the mod, if you got another version you might need to update it first.
