"Merchant", in this case, is a character who tends to do some speculation and enough varied skills to work passage aboard the ship carrying his cargo. For example, he may buy 3 tons of stuff and serve as pretty much whatever crew slots aren't filled. Of course, the Art(Chef)-2 really comes in useful.
Leitz,
Hmmm... so he's a goods speculator who travels along with his goods? He'll need some safe way to carry large sums of money then. Not cash mind you, but money. He going to need some working capital, you see.
First, he buys the speculative goods. Then he has to find a ship that will both carry the goods and allow him to travel on a working passage. Finding a ship, especially when you consider the working passage requirement, means he might have to store the goods for a period of time. After finding a ship, he needs to have the goods transferred to the ship and stevedores aren't free. Once the ship arrives at the destination worlds, he'll need to goods moved and put in storage again until he finds a buyer. We haven't even touched on insurance yet!
Moving and storage is going to cost money naturally and he'll need a reserve to handle any unforeseen costs too. He can't have a Big Bag O' Cash because that's just an incentive for Cap'n Blackie and the crew of the
Running Boil to toss him out the airlock without his money. Bearer bonds offer the same incentive.
Your merchant will most likely have working relationships with a number of regional banks and merchantile houses that can provide him with letters of credit. Those will be documentation telling people that Merchant A can be given X number of CrImps because he's backed by Bank B or House C. This documentation can be as fancy or as simple as your campaign requires.
The DM for the game shared an idea about a ring that trades business information, the "modern" equivalent of a business card exchange.
That's a nifty idea, some sort of automatic info-exchange device right? He walks into a company's offices and his ring automatically gets an updated catalog of their goods and services that he can latter peruse. His ring in turn gives the company a rundown on the goods he can offer. Sort similar to the RFID tag technology some stores are beginning to experiment with.
Regards,
Bill