The way it currently operates the AI thinks their ships are gold plated and yours are warm summer garbage. Considering what the AI is willing to offer in ship trades the feature might as well not exist. It does make sense that they wouldn't want to weaken themselves for some coins, but but weakening me and strengthening themselves seems like something they would consider.
The price of ships in trade should be closer to the price you could buy it for in a shipyard with some modifiers. Increase value if it includes technology the buyer doesn't have, or exceeded the mass limit due to modifiers the seller has but the buyer lacks. Also the AI should be willing to pay more if it has below the average manufacturing capacity and fleet strength.
Lastly there's the AI not recognizing its current situation when trading. They can be in a desperate war and I can clean out their treasury by trading them new farms, however they'll try to lowball the unstoppable juggernaut I'm offering them. When at war they should prioritize what will help in the short term rather that building an empire that may not exist.