To start things off I need to make sure everyone knows that most of these resource stockpiles and stuff are 32 bit signed integers, supporting 3 decimals. which means if you can make anything cost more than 2.1 million, it overflows and becomes free.
Communal Habitations district cost increases linearly by 25. This makes it stay super cheap into late game. However, if you start a fresh city and start spamming it, you can actually abuse this cheap price to inflate other districts. What I found is that after buying about 15 districts of the same type, it actually becomes cheaper to then spam Communal Habitations until all other districts hit the ceiling and overflow. Looking at the first screenshots taken at the same moment in time, you can see the research quarter is starting to skyrocket in cost, however, the Communal Habitations stays super cheap. Even to buy just a single research quarter, this is the most cost effective way, let alone you are going to get more than 1 for free.
Looking at the first 3 screenshots, you can see we can either buy a research quarter for 2.09M, or a communal habitations for 5.5k. In the third screenshot you can see after paying 5.5k for the communal habitations, we hit overflow and can build research quarters, and in fact, any other district for free. Overflow gets hit at about 90 districts, and territories hold about 35 hexes each. The Kin for example can hold 5 territories on capitals, which would mean they could hold 175 districts total.
I am still testing other areas of the game but inflation and overflow seem to be a huge issue. In the last 2 screenshots you can see I also inflated the stock market and made well... 17772 x about 6960 per... equally about 120M dust.
Spamming communal habitations leads me right into my next point, reaching overflow on last lords population buyout. Once you hit that 2.1M pop cost you get the rest for free. And there are ways to hit that ceiling quicker, by using the Round Up ability. LIMIT REAC

~~