This is great!
However, one point seems to be problematic: being only able to buy at your starter puts a great disadvantage on anyone who settled out. You should think of implementing a player being able to switch the trade hub location asap.
Edit: Also, the market can be misused to transfer huge amounts of ships immediatly from one alt to another, without having to pay the uranium required to send them.
This is definitely a possible next step.
With regard to the misuse - yes, you can do this, but you will have to pay the market fee of 8%.
If you should think of just putting a low price - than somebody else might buy your ships, so that is risky