1.availability - I try to support local stores and only order online when it cannot be ordered locally- although - sometimes online prices for dry goods cant be beat
2. how perishable the item is (no point in ordering livestock if the shipping will kill it)
3.ease of shipment (the higher the weight/size of the item, the more it'll cost to ship, ie. salt)
4. technical aspect of the item - i really do need help with this stuff!
5. fragility -not too worried about this one, as most vendors will package products accordingly