I propose this:
Logic:
* Wares move from left to right.
* If they're manufactured, Production column is involved. Otherwise they go to output.
* The station ONLY buys things from Import zone.
* The station ONLY sells things from Export zone.
* Storage is just that. Storage. If it is input, station takes it from storage, if it is output, station places it there.
* The user moves wares between import/export and output with a click.
* Trade rules apply.
In this scenario the manager only needs to use budget for things from Import column.
This can be refined in many way (like splitting between import and storage or having those present simultaneously), but I think this would already be an improvement.
Basically, because station has no conveyers and no topology, there's no real reason to have a complex flow graph of goods we have now, and at the moment scrolling through it or trying to shut down all the unneeded buy/sell orders is not exactly fun. This version cuts down everything unnecessary.