Cousin Ring in the Evnici system is a decent starport.
You can buy the following (plus more):
Asp 6.6 mil
Vulture 4.9 mil
Cobra 380 k
Viper 143 k
Also has a black market.
Outfitting options seem plenty.
As for trade, you can sell the following selected items:
Consumer Tech 7533
Performance Enhancers 7533
Progenitor Cells 7533
All of those listed above are selling for at least 500 above the galactic average (one or two of them are 1000 above)
All hail the Emperor