I would like to discuss the one time 100-140 gold to get a corp in a city for just a little bonus. The little bonus is often something like 6-12 hammers or 6 food and 24 culture easily. That means that that one time corp is paid back in less then 20 turns (saying 1 hammer is worth 1 gold for instance). The advantages of the corp outweigh the costs normally by far. Found a corp in a wall street city and you get 12 gold back per turn (minus the upkeep cost of -4 normally average) so the earn back time is reduced immensely. Not even counting the fact that cities with sushi and mining for instance grow enormously fast and build a lot faster, thus more income from trade routes/specialists/buildings/etc.... Corporations is one of the reasons I hardly use state property anymore. If you have some land to settle get new cities with corp agents and voila instant cities within a couple of turn and a courthouse/library/granary etc....
The problem is propably the fact that you have very little resources from a certain corp. Say you found cerial and only have 2-3 food resources for it, then it is not worth it propably. But if you can trade up to 6-8 resources for it, then you will see how well corps work. A little advice, try a fantasy map with crazy resources (for instance rice as a crazy resource and then see how incredible powerfull corps can become).
The problem is propably the fact that you have very little resources from a certain corp. Say you found cerial and only have 2-3 food resources for it, then it is not worth it propably. But if you can trade up to 6-8 resources for it, then you will see how well corps work. A little advice, try a fantasy map with crazy resources (for instance rice as a crazy resource and then see how incredible powerfull corps can become).