OK, those are numbers I understand. The difference in perception probably comes in when counting fuel supply. Yellorium is hard to accumulate if you mine manually, but much easier if you do random automining, since it's equally distributed unlike GT ores. Which means you can put down an Ender Quarry anywhere and get usable amounts of yellorium from it. It may take some time since most likely you won't be able to run it at high speed, but nonetheless I count it cheap because I don't need to do anything except to wait, and at standard speed it doesn't cost more power than an MV EBF. Thorium is much harder since you need to go prospecting before you mine, manually or automatically.
In the end, it may be more appropriate to compare RTGs to other renewable power sources. I have used two other such sources: tree farm/coke oven/RC boiler and turbine, and fusion. I haven't run material costs for either, but I suspect they may be in the same order of magnitude as the RTG if you relate material investment to power output - and here we can dispense with the total time since all of them can run for an infinite time without any additional material requirement. The main difference is that both are *way* more complex, and as long as the matter is that RTGs are too simple to build you'll get no argument from me. I don't want the construction or the design to be easy, but yes, I admit that I very much prefer the running costs to be low to non-existent. With both the tree-based and the fusion-based power, the running costs - and I count "required attention" as cost as well as materials - were limited to having to repair (or replace) turbine rotors now and then. If this is possible at the 250 EU/t level and the 25000 EU/t level, I don't see why it shouldn't be possible at the 2500 EU/t level? Well, without spamming tree farms, anyway, which is boring.
