This is what I know.
At the grand exchange: Find an item you want to buy -> Buy it at 10% above standard price -> Sell it back at 10% below standard price -> Right click the Grand Exchange clerk and select "history" -> Write down the highest number for the item (what you bought it for, at 10% above) and the lowest number you sold it for (what you sold it for, at 10% below) !! (notice that these numbers are not exactly 10% above or below standard - it's just what they're going for on the market currently) -> Subtract the highest price from the lowest price to get your profit margin -> Buy the item at a few GP above the low price and sell it back at a few GP below the high price (to ensure sales, or if the price margin changes)
Is there more to this equation?
At the grand exchange: Find an item you want to buy -> Buy it at 10% above standard price -> Sell it back at 10% below standard price -> Right click the Grand Exchange clerk and select "history" -> Write down the highest number for the item (what you bought it for, at 10% above) and the lowest number you sold it for (what you sold it for, at 10% below) !! (notice that these numbers are not exactly 10% above or below standard - it's just what they're going for on the market currently) -> Subtract the highest price from the lowest price to get your profit margin -> Buy the item at a few GP above the low price and sell it back at a few GP below the high price (to ensure sales, or if the price margin changes)
Is there more to this equation?




