-hot streak (store visits per single item with over $100 profit at market)
-grind value (store visits per item with any flippable value)
-sunk cost per visit (gas, time, etc) over net sales
-some way to calculate which stores or neighborhoods are most likely to yeild
At this point I only really buy stuff I need for myself or something I just cant pass up. Mostly because of Canada Post's expensive shipping rates.