I hear you about the different warehouses that RockAuto uses. I've backed out of ordering items because of that. Overall (if everything is coming from the same place) RockAuto is reasonable on shipping costs. I bought a rocker panel from them and expected to get put over a barrel on shipping, but was pleasantly surprised when the cost was reasonable.
Amazon Prime offers "free" shipping (that you actually pay for), but you have to watch out for jacked up prices. They're not always the best price. I just saw that Amazon was dinged for penalizing vendors for offering items directly for less than what they sell for on Amazon.
I've bought electronic stuff from DigiKey and received a box with a cubic foot of packing material and a small envelope of resistors.