It goes both ways..

If it's green on their side, that means you're getting a good deal if you're buying from them, while if it's green on your side, that means you're selling at a good price.

Let's take Planet Manhattan for example. It's the best place to get consumer goods, because they're selling them for cheap, so it's a good deal if you buy them. Once you buy them, they'll be listed on your side, but the status will become red, because the price for selling them is low, and is not a good deal for you to sell them at Manhattan.

The whole colour coded thing applies for the entire game universe, which means that it involves the bases that you have not visited yet. You may still be able to make a profit despite the colour, but it will not be as good a profit as one where you buy and sell with green status.

Hope this helps!

I find that if you're planning on doing some trading in the future, then you should dock with every single base you come across. Just dock and take off again, if you don't have any business there. Once you dock at a base, then full info about it will appear on the map, and when you're buying/selling commodities the prices that each base that you've visited are listed at the bottom.

Also, on some commodities (especially cheap ones) the red/yellow/green seems to lie. I've had the cheapest scrap metal in the galaxy marked as yellow or red to buy, for instance.

ER