It was around 130k, so I'd lose a bit of money at the end of the month but as I said, I still had plenty left. Even if it did use up ''only'' 130k it shouldn't take this long.
EDIT: Here's the latest month I caught, wasn't exactly 130k but still more than enough to finish under 4-5 months tops
Spoiler
(https://i.imgur.com/y48eVOv.png)
Was there anything else in the queue, or was it just a Niagara?
Spoiler
(https://i.imgur.com/JQidp5p.png)
Just a Niagara 100%, even the quantity is 1.
@Mondaymonkey
Now that you mention it, I did take some supplies from the stockpiles, but that was only 2 months out of 10 and it was barely even 30k worth of it.
In the end, none of that matters, just seeing ''Production cost this month: -150 000 credits'' 3 times should be a sign that something's not telling the truth. This is why I said it should be easier to track your orders.