The Town Map?
What thing could possibly be so important it's at the top of each page? The Town Map (did you think it was going to be something else? Rawl it all, this is a horrid intro they've written). It can get you to the store you need. There are, of course, five different types of stores:
The General Store
Can sell it all. Except if you want to discreetly poison someone. Other than that, a General Store can have it. It's not guarenteed it'll be in stock, but they have the option.
At an apothecary, you can get those nasty items which don't require brute strength at all. A haven for the weak and womanlike, eh? Get yourself a poison for someone you don't really like, or buy up some elixirs to improve your dueling skills.
This'll get you the joy you need in your life. Ships, as you will quickly discover, need two things to really survive: a hefty dose of merry, and some profit. This is your dose of merry. Different selections will give you varried results, for varried prices.
Sells supplies to help out your ship or submissions. Got a torn hull? Repair it here. Need to tear a hull? Get some thugs to do it here.
A Blacksmith can sell you all the items you need for dueling. You only need one of each (myself, I know a good few smiths that've gotten a hefty sum from that bit of mystery). Get your weapon accessories or weapon upgrades here!