For example did some checks on other reactions. (not using in game figures but from dotlan so with all the precautions from that)
First I noticed that Vanadium Hafnite has increased in value significantly, it is now at 4.5k/unit (was half that a while back) Vanadium and Hafnium has increased as well, especially Vanadium which is now around 1.1k/unit.
So I checked the advanced reactions using it.
There are two, hypersynaptic fibers and phenolic composites.
Fibers are more valuable but they use around 1.8bn/month pure bought materials so out they are out of the question for that reason imo.
However from the less than thorough analysis I found that composites will in total (including intermediates) give about 830m/month in profit before towercosts. That would be placed at a hafnium moon in Bimenen. I do know of a vanadium moon in gw but it is far in, although in the place where I think it can be possible to run mining ops so could be a option to place a pos there but that is also a position I'd rather hand to the alliance to draw them into holding poses in more dangerous areas

Total investment would be similar to the first tower I set up (even have the spare tower which haven't been sold yet) so wouldn't impact the wallet that much. Going to check trends and such a bit more before I make any real investment into this. But with these two reactions we would have a approximate income of about 1.6bn/month at current prices after pos fuel.