Would it be possible to have a buy only trader?
Same as the trader buy list system only it updates the buy orders but wont sell?
The filaments are getting expensive but could save 300k per if bought on buy orders. 7.5 mil an night x 20 = 75 mill or more a month.
Same with ammo ships and drones fittings - could be upwards of 300 mil a month.
Plus I like to build big things and would increase my profits for PI as well.

If u manually set up a corp buy order I think the bot will update the orders but won't be able to sell the items because they will be in corp deliveries. So this should do the trick for you