I actually did something last night that inspired this topic.
I sent a nasty tell to a guy who was cutting my throat with undercuts. I had spent most of the day sick and cranky, and after watching him drive the price of my current item down from 4k to 2500 over a couple hours I mentally flipped a table and typed out a nastygram.
Long story short, what resulted was an undercut war that drove his price all the way down to 1100gil. ...at which point I bought him out and pulled all of my items off the MB to sit on the whole pile. Following this we had a lengthy conversation via /tells (much more pleasant then the one I had sent), and he turned out to be a pretty decent guy. But he didn't have much of an idea how economics work. So here we go:
The First Core Rule: -Everything- has a value in gil.
The Second Core Rule: The speed of selling is based not only on UNIT price, but also on total STACK price.
So what does it mean to say that "everything has a value in gil"?
Exactly what it says on the tin, but lets extrapolate. Say I'm cooking Buttons in a Blanket to sell on the MB. The current going rate is 2000gil each for NQ, 3000 for HQ. Stack sizes vary from 10 to 25 (this will be important later). Taking the NQ as an example, we say the "value" of one Buttons NQ is 2000gil.
But what are Buttons made of? Five each of fire and water shards. Midland cabbage. Clove oil. Three button mushrooms. Desert Saffrom. Tomato sauce. Those items all have "value" in gil also, before you synth them.
Lets say we check the market board, and Fire and Water shards are 100gil apiece (pretty typical on my server). Well that's 1000gil just in shards you're using just to make buttons. Desert Saffron is worth 200gil, cabbages are 250 gil, tomato sauce is 25 gil, and clove oil is 100 gil. We're at 1575 gil just in materials, NOT COUNTING the button mushrooms! Add three of those and lets say our total "value" in mats hits 2100gil.
Houston, we have a problem. The Buttons that we can exchange for a "value" of 2000gil, are actually costing us a "value" of 2100 gil. A loss of 100gil ON TOP of the time lost sitting down and synthing them! You should have just sold all the damned mats on the market board!
What does that tell some people (namely undercutters)? Well there are two very common mistakes that get made. One is from people who gather the mats for their own synths. Since the mats were "free" as in didn't cost any gil out of pocket, they don't perceive any loss in value despite the math we just did. And the other is to forget that TIME has a value in gil also. If you're out gathering Button Mushrooms worth say 250 gil apiece, why sell those at a loss of 100gil value by synthing them? You could instead use the SAME GATHERING TIME to gather something more expensive and sell it directly on the market board. Same time spent, more gil earned. You could even then BUY the button mushrooms from someone else and pocket the difference if you insist on synthing them!
Everything. Has. Gil. Value. EVERYTHING.
Some times there are easy solutions to these problems. In the case of our Buttons example, we could just use a macro to HQ them. Now we've got from a net 100gil loss in value to a gross 900gil gain.
Or is that really a solution? Macros take TIME to run, don't they? In the amount of time you could craft say, 30 HQ Buttons with a macro, netting you a "value" profit of 27,000gil, how many expensive items could you have farmed up with your Botanist? What would THEIR value be? More or less than 27,000? If it would be more, then you should be out farming instead of synthing HQ Buttons.
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The speed of selling is based not only on UNIT price, but also on total STACK price.
This means that when people buy things on the Market Board, they're looking at more than just what each item individually costs. What they're REALLY looking at is: "How much gil is going to come out of my pocket when I click this button?"
In pactical terms, this means that UNDERSTACKING, is just as good, and maybe better, than undercutting for getting your items to sell faster.
If the MB has 27 stacks of HQ Buttons in a Blanket up for sale, in stacks of 10 to 25, for 3000gil apiece, what looks more attractive to the buyer:
A: You put up a stack of 15 HQ Buttons for 2800gil?
B: You put up three stacks of 5 HQ Buttons for 3000gil?
In option A we have a total price of 42000gil. A savings of 3000gil compared to your competitors.
In option B we have a total price of 15000gil. A savings of 15000gil over your next lowest competitor.
Now we know that it isn't really "savings" perse, since the buyer would have to buy two of your stacks to get the same amount, totalling the same gil. But it DOES save them value in out of pocket expensive, because they don't need to spend all that gil at ONCE. Many, many more people can afford to toss 15k out of their pocket for some food for a quick Coil run than those who can do the same with 30k. By understacking, you've essentially opened your sales up to a poorer market, giving yourself many more potential buyers. This means that your smaller stacks will sell faster than the larger stacks of your competitors, and you don't have to undercut and lose value to do it.