I can recommend filterbag.com. I've bought filters from them. I recommend the nylon filters. They are washable.
As for how to do it. Like anything homegrown you'll get a million different answers. I'll tell you how I do it.
I get my oil 2 ways. One in the 5gal jugs it came in from one place. The other I suck out of a 55gal drum I've placed behind the store.
When I filter I am always starting with a 5gal jug of oil.
First I let it settle for a few days, the I siphon off any water that collects at the bottem. (If you are starting the siphon by mouth, be carefull, the water sitting under the oil is nasty nasty nasty nasty
).
Then I filter it to 75 microns using a bag filter into a cleaned out 5gal jug (I don't clean it each time. Just cleaned after it had unfiltered oil in it). I typically filter 2.5 gallons at a time. Mostly cause you get tired of lifting a 5gal jug of oil. When the oil doesn't quickly pass through the bag I stop and let it drain, then wash the filter. Then I let it dry for a day or so. If I am in a hurry I whip out the hair dryer to dry the filter (low, carefull not to let it get too hot, it is nylon after all).
Then I filter into 2 different 5 micron bag filters into 2 more cleaned 5gal jugs (same deal, they aren't cleaned each time, but certainly are if they've had anything but 5mic filtered oil in them). I'll filter into these these jugs till they are full. Since I also use these as my fuel cans. When the filter stops flowing well I'll pull them out and use a new filter and clean the old ones.
I have 1 75micron bag filter and 10 5 micron filters. I can usually filter about 10 gallons of oil before I need to wash the filters. I realize I could probably get more use out of the filters if the system was pressurzied, but I don't feel like spending $600 on a peice for canisters for the filters. This way involves a little washing, but the cost was only in the filters themselves. So far I've filtered about 500 gallons through these filters and they aren't showing any signs of wear.