What would speak against nerfing the costs of the reactor components, though?
5.3 copper ingots, 2 tin ingots, 8.5 iron ingots for a god damn basic B fan, really?
I consider reactors currently to be balanced ( except for the fermenter part of course). If you would like to nerf its costs I think there are two things that should be taken into consideration:
1. As reactors are generators, their costs must not be too low to make other generators unreasonable to use.
2. Self-sustaining reactors must not be easily accessible in a large scale.
As the whole generator balance thing is a rabbit hole that affects the fundamentals of IC2, I'm not very willing to go down it and therefore leaving it to you guys.
Large scale reactors are basically end-game, which is when you are likely to have accumulated a large amount of basic ores via automated mining. So rather than material costs manual labor needed is of greater importance. Crafting of vents can be automated too.
Something that has bothered me about reactor vents is that they incorporate an electric motor in its recipe, but they don't require any external source of power to actually vent out heat from the reactor.
Might be more fun and challenging if you had to supply a small amount of power for each vent to remove the heat from the reactor. Forgetting to power the vents would lead to a meltdown.
I would assume that the vents are powered internally. How would you like to power the vents then?