I am no expert, and madmax clearly has done his research. The price of those jerry cans are high. I just bought a ceramic and carbon filter in a simple siphon setup from here:
http://www.purewaterproducts.com/gravity.htm
Read all of the related articles. They say you can filter dirty pond water. Probably the simplest method is let settle, treat with chlorine bleach, 8 drops per gallon, then filter with the candle and carbon. This setup costs $61. My brother and I went in together and got two, so $56 each, shipped.
The ceramic filter works fairly fast siphoning, and will drain the container it rests in. It stops siphoning when the container is empty. It is silver impregnated and washable/reusable. The carbon filters they sell are good for 1500 gallons of water for chlorine removal, and cost $15 to replace. You could also find replacements at Home Depot.
This is simple and inexpensive.