Electric Generators?!? Help

Alright, i am looking to rent out a garage somewhere that is secluded and secure but it is harder to find ones with electricity. Are electric generators worth it? I need one that can handle 1500-2000w because i have 2x400w hps and 1x250w cfl and some other things but would like the opption to add an extra light or two. How long do they run for and how much are they to run?
help will be appreciated
Thanks

sorry but you wont like the answer, my little generator puts out 1000 watts and will run about 8 hrs on heavy load,10-12 hrs on a light load.1 gallon tank. my 2500 watt will only run 5-6 hrs on a full load w/ a 2 gallon tank. you will use about 4-5 gallons on a 12 hr day. if you are anywhere that gets cold at night,you may also need to run heat as well. sorry but its not going to be cost effective & a pain to haul all that gas.