There is no maintenance cost for any facilities. DS just meant the build cost. But, that is not a good way to compare them, because the increased production rates offset the build cost of Robotoids and such very quickly. You lose at most 4 turns of production from a mineral miner when building a planetary Robotoid, and System Robotoids provide so much of an increase that the extra build time is even more irrelevant in most situations. The build cost of the facility is really only a major issue in Proportions mod.
