So you have a ship and a crew, some chemistry equipment and a doctor type. It turns out that a local government suppresses the psionics in their population. One way they control them is to naturally ban drugs that boost psionic powers. You can synthesize those pharmaceuticals on your ship. Your ship that has a hefty mortgage. Your that brought in a load of electronics that you planned on trading but that were just recalled or made obsolete by recent advances.
Breaking Bad meets Firefly.
There are a bunch of ways this can spin out of control in a Traveller meets Fiasco sort of way.
The plan to cook boost could be hatched by one or more crew members without the captain's/owners's direct knowledge. They just cook the books as well to make it look like there's a profit.
The production doesn't have to be onboard the ship. Simply 'deliver' a crate of lab equipment to a location you rent, do the production while you're on leave, sell it and bring a crate of lab equipment to the starport for delivery.
You're going to need a delivery network of some kind. A week is not a lot of time to produce the pharmaceuticals and sell them. If your ship works a regular route it gets a little easier. You can build a network of contacts to accept delivery of your product and bring it to the customers.
But that is where it gets complicated. How well do you know these contacts? How well do you know the psionics involved? Your contact could decide that the pharms have really lucrative recreational uses. That can lead to him pedaling them on the side. That may mean he orders more than he needs. Not a problem. Or he could start diluting the drugs to have more to sell. Cutting drugs with other substances can have all kinds of side effects. You don't want to talk about side effects when you're dealing with psionic people. An overdose that ends up in the hospital or the morgue leads most police to ask questions. That can lead to them finding the psi institute or your contact who might start talking to lessen his sentence or torture period.
Naturally a new drug appearing on the street will make unsavory types who view those streets as their property very curious about who is doing it and how much of a cut they aren't paying. At that point the police may not look so bad. Or we can invert that trope. The crew finds another crew trying to push into their market doing all kinds of fun things like beating their buyers up, ratting to the police and selling tainted pharms under the crew's label.
For the win, give the crew the chance for a big sale, one that taxes all their resources and finances to put together, then legalize the stuff. Their mortgage is still do on the ship but surely they've been saving their ill gotten gains?
In my Ghost Drive setting the Empire and the Ghoul Cultists are both likely targets for the scheme. In fact given the way they oppress their psionic populations it could be seen as aiding a resistance against oppressive governments. That might justify the sale of the stuff for more recreational purposes. Your players' morals may vary. It should be noted that resisting an oppressive regime is seldom black and white. People on both sides will over react and innocents will suffer. Yes even evil regimes have innocents in them (see Randall's rant in Clerks about the contractors aboard the second Deathstar for a good example.)
Suddenly simply making ship payments is not so simple. What the hell. The crew can always just hang around a bar and look for a patron.