The secret of Frontier is finding a good trading route to build up your credits and here is a good one. Firstly you have to find Cemiess (it's an Imperial-controlled system to the left of Ross 154) and locate its bulletin board. Here you should see an advertisement for goods bought and sold and that someone is willing to pay 3000 to anyone willing to take some precious metals off their hands - sounds like a dodgy deal but you've got to make it while you can. Stock up on as many of the metals as you possibly can and then take them to Tivea to sell. Once you've got a substantial amount of money buy as many robots as you can. You should then take all these back to Cemiess to sell.