Mike, I got my setup from my local oil distributor. I paid a little more than other sources, but I prefer to support local businesses; especially being new in town. You can get several different types of setup from Harbor Freight. There are also other online sources - one Google search I recall working was "farm nozzle"; found several suppliers of all the required stuff.
My own setup is gravity, but the only difference is whether or not you add a pump, either hand pump or electric pump. From the output, whether drum or pump, add a good quality spin-on filter, then a petroleum quality hose (mine was pre-made, 3/4", and 14' long), then a swivel, and then a farm or utility nozzle (similar to the regular gas nozzles, but without all the safety stuff). Since my setup is gravity, I also added a ball valve before the filter rather than depend on the nozzle to prevent the flow. I also had to add several pipe fittings to adapt to the barrel, and a vent setup at the other barrel opening. If you use a barrel pump, it should have the correct fittings and probably a built-in vent.
I don't remember the breakdown, but the total cost for everything was around $150 without a pump.