We did it for 5 years, and want to eventually get this place off the grid too. It wasn't easy although I think it was the best thing that we could have done, I learned a lot. We bought some land way up on a hill in western Washington and built the house ourselves, we had a small 4000 watt generator for a while but it didn't last long so we just did without it, We finally went to a large battery pack and a 3 1/2hp Briggs engine hooked to an alternator to charge the batteries, We were just getting some solar panels when we moved so we didn't get to try them out very well, I think they would have been great. Our water system was a big tank situated higher than the house which was piped to the regular plumbing, for about 4 years I hauled the water to fill the tank with a 1949 Chevy 2 1/2 ton truck from the creek, Dad finally built a hydraulic ram pump and pumped from the creek to the tank, that was the neatest thing I have seen, the hill it had to pump up was about 200 feet streight up, it was impossible for anyone to walk up without grabbing on to a rope or something to help, that pump pumped all our water up that hill for a year without one drop of gasoline or one volt of electricity, it was fun to just stand there and watch it go thump thump thump 24/7 all by itself, and it was so simple to make! We used 12 volt power in the house streight from the battery, if I were to do it again I probbably would get an inverter so appliances could be run. We had propane hot water, refrigerator and stove, wood heat and most of our lights were kerosene lamps, we didn't have TV, computer, etc. We moved from there three years ago, because we needed (wanted ) more land, hated the rain over there, and the driveway was too steep. We have 80 acres here and an older home, we are slowly getting it ready to shut off the power, I am doing things a little diferent here too. We have a much better wind source so I will be using that and solar power, we will keep the usual appliances, computer, tools etc. so we need lots more power than before, I will use the generator for the big things like welder and air compressor.
As far as economic feasibility goes... it depends on how fancy you go and what you are willing to do without, I have several friends who have built their houses off the grid from the start, they have water power which is great and would be my first choice ( I don't have any running water nearby) one aquaintence runs a 180 acre place with two houses off his creek, and has power to spare, one benifit is his power never goes out when the neighbors does! he never has a power bill and maintenence is very little.
If you have any more questions I will be happy to help if I can, Christopher