Another option, instead of raising costs, would be to make these two 'currencies' more valuable by increasing what can be done with them. Personally, I feel that the 'fixed borders' aspect of a number of civics actually devalues culture. (Admittedly, I turn culture victory options off, but that's more because I don't know how well scaled culture victory conditions are to the current abundance of culture buildings in the game.) I wish there was a way to completely turn off the fixed borders option, so that culture once again holds value in setting the borders between your nation and a neighboring nation. Additionally, I like that there are a couple of buildings that have culture level requirements in the game already. This is another thing I could definitely see expanded on to help restore some value to culture.
Ultimately, while I can see where a lot of people are coming from in saying that gold is too abundant, I agree with Joseph that the gold issue is only a symptom of the issue, not the cause. I think that, with as many buildings producing actual culture, espionage, and gold as there are now, instead of them being percentage modifiers, hammers have actually become overpowered. Say I want to increase espionage production to launch some sabotage missions against a neighbor. I could up the slider, but I could just as easily build come crucifixion crosses or town watches. Or say I need a little culture in one city to expand borders? I could up the culture slider, sure, but the dance hut is cheap and much more targeted than the slider. We've come to a point in this mod where hammers are able to be used as just about anything the player might want.
It's still on my list to revisit fixed borders and make them less draconian, or make them somehow vulnerable in indirect ways to culture pressure. This is easy to do by using the REV mechanics so that culture pressure in a fixed border situation (i.e. - one where ou are holding tiles only through fixed borders that are NOT really of your culture) to make revolutions in local cities more likely.
However, I still don't have a great idea for a non-REV mechanic so it works for everyone (including those not using REV). How would people feel about this as a suggestion:
- Fixed borders still means you can't lose tiles DIRECTLY to culture
- However, each tile you hold that is NOT dominated by your own culture (i.e. - ones you hold only via fixed borders) have a gold cost per turn, which increases the less your culture is present there (as a %)
- Some way to 'cede territory' is added so that the fixed border civ can elect to give up some tiles it holds to relieve the financial burden
- (possibly) (some of) the gold cost is actually TRANSFERRED to the cultural owner(s) (in proportion to cultural ownership) rather than just lost as an expense. This represents the population sending home money to their (cultural) relatives or something.
This doesn't invoke any REV mechanics, chews up gold as a side effect, and gives a benefit to cultural pressure as well as a cost to resisting it via fixed borders. The only issue I see is having the AI figure out when to cede territory (and possibly also figuring out a good UI to enable humans to cede territory)