If you find a few particular products that you have difficulty getting enough of Luke then you should manually order more (being careful not to exceed a safe cash flow) and slowly you will build up stock piles.
Most all longer term players here have stockpiles for emergencies when they need to feed their own corporations or transfer stuff between countries to keep a positive stock.
Obviously things in big shortage are going to cost you more but in the long run its better than not having the product and your welfare/supply index drop or corps not producing. Sooner or later you can stock pile stuff when its cheap

win, win, sell for profit or supply yourself cheaply.