I don't vend anymore but I used to refresh the just added page. I never learned all of the prices but I got pretty good at glancing at the charts and deciding whether to buy or not. Still missed a lot of deals but I got enough. As long as the volume on the item is at least 5 per day and the average buy price has been something you'd be willing to sell at for at least 10 days, you should be good almost 100% of the time.