Oolite Bulletins

What is the feasibility of this: when you trade in your old ship for a new one, your old ship appears in the shipyard, perhaps with all OXP equipment removed, and at a slightly higher price than what you traded it for (markup and all that).

Nice Idea, if it can be done I'd certainly like to see it.
And now we can name our ship it would be nice to see its name if its on the market.
I've always thought that the ships we see are all second (even twenty-second) hand, another nice thing could be that all the ships already have names when they are for sale.

At the moment, very infeasible. The shipyard code does need a significant rewrite at some point and making it scriptable should be part of that.

There is a possible OXP solution: you can make a second-hand shipyard in interfaces, save the player ship into a missionvariable using [wiki]Ship_Storage_Helper[/wiki] at every landing and eq changes, then restore when the player buy it back.
Storing of the last 10 ship is enough imho with long random timeouts when another pilot buy that ship.
Should save the place of selling to show the ship is available locally or must rent a pilot who will transfer the ship here for extra money and time in relation with the distance.

I think the idea here is probably not so you can buy it back, but just that, logically, when you sell a ship the shipyard would then put it on the market again. A bit like a used-car dealer does.
But that's where this idea would normally be pointless, because it would not appear on the forecourt instantly. Just like your car trade-in it would need some valeting done and possibly repairs and servicing as well. This all takes time, so by the time it would go back on sale you (the seller) would be long gone. It is really only if you stay for an unusually long time, or returned to a system quite soon afterwards that you might see it, but probably not as it might have already been sold again or even sold on within the used-ship trade.
Having said all that the concept is a good one and logically your old ship should show up for sale somewhere at some time. I just doubt that the effort required to make it work is worth it because if the system was 'realistic' you almost certainly wouldn't see it anyway for the reasons detailed above.