My approach to my merchant is to not worry so much about what the townies buy. Sometimes they buy high, sometimes they buy low. I want my merchant to be very rich and the way to do that is with a lot of sea trading. Of course there are days when her responsibilities involve opening up the stall and selling. What I have done, (I'm a tad OCD), is stock everything the store carries plus the things left over from my trading and do it more or less by category. All the armor and weapons are together, next is musical instruments or other gear, meats, fish, fowl, things to make drinks with, fruits/veggies, wood, gems, minerals. Each thing has it's own category. Why? Because when I've done my responsibilities I want to hit the road and it's much easier to upload and then do a take all at the end of trip.
The hard part is loading up but if you keep it organized it also helps you see what sells and for how much so you can choose which trip will give you the biggest bang for the buck. So far no one in sea trade buys water,sale, spices, honey or eggs so those items I can put in my larder and just load them into the stall in smaller amounts at the end of the upload. Why put them in the stall? Well, water really isn't worth the bother because you can only sell it for what it costs. Of course, if you draw it yourself you eventually make a profit but it is so small it really isn't worth it. Bottom line is I will only buy and keep tiny amounts of those things, and ONLY if they are a hot item or I can use them myself. But I buy out certain items because the profit margin is huge. Let's take the simple wildflower. In spare moments you can pick a few or buy them fairly cheap at the store. But they sell to Tredony for 78 simoles each! I'm having the most fun with my merchant.
