Now it has two recipe modes.

Cheap - basically available as soon as the railway is researched, early Nauvis
Expensive - available after Fulgora

The current scheme suggests a difference in costs, not in the game stage. It is assumed to be a multiplier, or maybe some additional, more complex-to-produce resources.

Also, it feels like the cheap option is too cheap; thus, we need some option in the middle.
Late nauvis? (with a pair of discharge defences, as a reasonable source for tesla equipment)
Maybe Vulcanus (for tungsten)