Good call. Here's what it would cost:

x To upgrade a Poor districf to Comfortable = 3 Wealth, 5 Personnel
x To upgrade a Comfortable district to Industrial = 4 Wealth, 6 Personnel
x To upgrade an Industrial district to Rich = 5 Wealth, 7 Personnel
x To upgrade a Rich district to Aristocrat = 10 Wealth, 14 Personnel

I've added a bit more info to the first OOC post, if you wanna learn a little bit more about the new Aristocrat districts. :>