I sell products with high purchase limits (10k-25k). I tend to OSRS gold flip. I concentrate on foods, runes, and pots. I track a few items that i know crash frequently and earn money off that too. I'm constantly switching weapons and armours that i make use of to protect my money , and also earn more often. Ie sold my bgs before it crashed to 8 mi, sold my fury before it crashed, and then bought one for 13 mil . I auctioned it off for 14.5 mil. We bought claws and lent them out at 1 mil each and was sold. Since arms and weapons generally go through a decline, it's beneficial to keep things in check like this.
I cant flip barrows or any other weapon or armour for that matter very well. Tips? I'll buy almost everything that people are trying to sell at a rapid pace and then make a profit off it. Ie my fury example. I also made 150k profit off someone who was rushing to sell his whip, for one mil. Similar to that.
My time to flip is based on the price's trend. If it's rising then i'll max buy at the current price (how I calculate max and min prices will be described below) before selling them at their max at the time the transaction is over. Sometimes, I buy/sell them for 1gp more than min/max based on the profit margin and the speed with which i am able to purchase or sell.
If the price of the item is declining, i'll purchase at min price and immediately sell it at the maximum price but still purchase at the min price. My reasoning for doing this is because if i wait between 10 and 10 minutes to max buy an item that is trending down, the max will lower in the same time.
Now , how do I find the "true" max and min. I purchase 10 of an item more than the price Then I sell it for way less than the real price. It will refund me the money back if I buy more than. Then , it will inform me what it purchased for buy osrs fire cape. If I sell my house for less than that, it will give me much more than what i asked, because that is the current min price.