We all know how the Ship Market currently works. Someone builds whatever ship they can/want to however they want/think which would sell best, and someone else looks in the ports for a ship they like. OR people broadcast a desire on chat.
In the Future, what about a Ship Market where the BUYER puts up a proposal for a ship they want of what build type they desire and a price range they are willing and able to pay. Once placed after some time the proposal is displayed in other ports nearby of the same nation and progressively spreads farther over time, after some more time it begins to spread to ports of other nations starting around the port of origins and spread slower than it did to same nation ports.
Once a prospective builder is interested finds the proposal they mail the other person from a link provided by the contract and they start negotiation and set up a time to meet when both are online.
When they have come to an agreement they initiate something similar to that trade window (though it would be ideal if somehow this window did not require both to be in the same port) but instead of trading its a contract window in which the agreed on parameters are 'locked in'
In the contract window the buyer would first submit the contract then the provider either accept or modify and send it back for approval, this would go on until both were happy.
The Contract would contain the ship, ships build, price, deadline, and location of exchange.
If the provider does not provide the ship by the deadline they pay a % to the buyer
If the buyer does not buy the ship they pay a % to the provider
I know there are some rather big things to resolve with this, but this is just a basic proposal.
alternately they could just do for ships what they have done with other goods. contract for a specific ship and build, someone brings the ship there and sells it to the contract and then the contract is claimed.