Lacquer is lacquer, and without any special bother, the lacquer could be tinted opaque black, the cost of the job should be no more than a regular re-finishing.
BUT.... colored instruments are most usually liked only by the younger student players, middle and high school. They think it is cool. Ergo, "kid's taste."
Whether you plan to trade it to an instrument dealer as credit toward an upgrade purchase, or going to sell it outright, It is far wiser to leave it with its traditional finish.
If it is in desperate need of re-lacquering, and you trade it to a dealer, that will be done at their wholesale cost, and you would have spent full retail to have it done, not really increasing the desirability or value of the trumpet.
The most practical thing to do, trade or sell, is to leave it as is.
Best regards.