I think the ship buying/selling could be merged into a tab on the market screen. The ship buying already has a similar structure, with the same markets (standard, black, military) as the commodities, so I think this would be a minor change. The hotkey 'F' could still take the user to the ship buying/selling - it would just be a new tab.
Usually when I stop in at a station or planet, I check what weapons, commodities, and ships are for sale on all the markets. This is a little awkward because, while the buy/sell and sorting tabs in the fleet screen and market screen are hotkeyed, the various submarkets are not. That means a lot of clicking as I switch between markets, then do it over again.
Thoughts/feelings?