1) I noticed that there is free space in the lower part of 'Review Expenses' panel (Panel 5-3-2). It shouldn't be left unused. My biggest gripes (?) are about 'production costs'. This item is always the biggest and most obscure one in the budget expenses. My suggestion would be to divide it into 'production' and 'investment' (assuming that currently investment costs are part of 'production costs' . It would make it bit more transparent.
2) There seems to be no info about maintanance costs before you have actually built the upgrade (correct me if I'm wrong). In most cases the maintanance costs are not very high and it is not important to know it. But in some cases, especially in 'first world' scenarios, where GDP is very high, the maintanance for some factories is well beyond 1 billion per year. This number is high enough to consider before actually building the upgrade.
So my suggestion is to include estimated maintanace costs either to 'construction estimates' panel (Panel 6-select specific industry-1) - there is enough free space for it.
Or even better on 'Confirm upgrade placement' popup because this is the place there you set the production level of the upgrade and maintatnace cost depends on it.
No, I won't stop making suggestions just as you finally want to lock the interface. On the contrary, most of my (groundbreaking) UI improvement suggestions I will make two days before the release.
Ain't I evil.