Below is what i think that "market opportunity" means: a relatively high volume item don't have enough supply and by checking the item's price history i see that there was a high order filled. I though a bit and decided to buy first 2 orders and resell them at 1.5mil. I know that i will be undercut but that's why i chose 1.5mil as starting point so i have from what to cut. I hope in a ~25 to 50% profit overall.
Also i invested in other items that i think will worth, gonna see if they sell fast enough.