i can tell you that it is possible to make enough money, i for example am paying around 800k every 3 hours and can still keep things way up, altough it was tough at the beggining once you have some money you should start buying from merchants that sell at low prices and sell to merchants who buy at high prices, luck is a major factor there.
another way is to just obliterate an entire faction and rob them of their resources wich you can sell for profit only.
i'm currently trying the second method since some weak faction made me angry by not allowing me to sell them some goods XD
the first option took me from 250k to 100M in a few hours, i was very lucky because i found a trade route in a sector that bumped me from 3M to 90M.
hope you understand what i'm saying cause i can be very confusing :)
Edit: forgot about pirate and alien hunting on yellow spots, after killing them just blast their ships and retreive the turrets and modules and sell them as you sugested its quite profitable too