What I did for this:
In the game, the very beginning there's a part you'll have to work to make 1k to buy 2 items or so. I basically made the 1K then bought a house instead (played as a "good guy" btw, I set the house payments on Normal, it still doesn't seem to affect morality, at least it didn't for me) I then worked on another achievement, make 20 villagers love you or something (or friends..whatever

)
I did invididual quests, and by the time I did a quest or two, I had enough to buy another building. By the time I got that achievement, I bought the entire village (that was able to be bought anyway, a few buildings you can't). After that money was easy. Had around 7.5 mil for the treasury and around 3.5 personal as well. And you really don't need anymore gold than that anyway. (And I was married to Elise and a couple of others paying 1k in upkeep as well)