Gold mined = free
Gold sold from miner = half of the best price available
Gold best price = 1600 tripoli shipyard
Miner sells 1000 tonnes for 800k
Diamond mined = free
Diamond sold from miner = Half the price of best price available
Diamond best price = 1600 Planet New Tokyo
Miner sells 1000 tonnes for 800k
Niobium mined = free
Niobium sold from miner = Half the price of best price available
Niobium best price = 1500 Lepzig station
Miner sells 1000 tonnes for 750k
ETC for any other materials sold
I think the selling prices are the same but i am only saying this from memory. might be wrong.
This method ensures the transport and the miner recieve the same amount of profit. Escorts are paid 100k each per selling by each trader
Escorts are paid 100k by the miner when a transport arrives to pick up wares.
(may need tweaking but i think thats the way to go)