We Need More Writers!
I came up with a very simple system for eyeballing markets to know instantly if they are profitable or not. Since we know that 15% of your sales get eaten by fees on the Trading Post, many players have resorted to multiplying the sell price by .85 or dividing the buy order by .85. This is rather time consuming if you have to check every single item that you're posting. My solution is so simple it will have you calculating profits on the fly without constantly having to input the numbers into a calculator.
Since 15% of sales go to fees, we know that every silver equals 15 copper in fees and every gold equals 15 silver in fees.
So when I see an item that will sell for 2 silver 20 copper, I do the following in my head to find the fees:
2 silver = 30 copper in fees.
If the buy order is lower than 30 copper less (1 silver 90 copper) then it's profitable for a flip.
See how easy that is? Let's do another where I get a little more complicated...
An item sells for 4 silver 50 copper.
4x15 copper = 60 copper in fees.
5x15 copper = 75 copper in fees.
I know that 4 silver 50 copper will then have fees right around 67.5. So As long as I get the item for less than 3 silver 82.5 copper it's a deal.
That one example was may seem intimidating, but I could make it a whole lot less complicated by simply saying: if the item can be bought for less than 4s50c - 75c I know it's a great deal. Use this strategy however you want, either with the complicated way (if you can do that in your head) or the much simpler strategy of rounding up to the nearest silver and taking away 15 copper times that amount. Obviously with gold you take 15 silver per gold, and honestly I ignore copper when I'm selling an item for more than 1 gold.