Hi i just had a look at some generators on ebay and initially the cost for them is high but your bill would go down so if youre going keep growing over time you will save far more than the generator costs (i mean they even sell 'LPG' fuelled generators)
So for generators your choice is:-
1-ELECTRIC
2-LPG
3-PETROL
4-SOLAR (THOUSANDS)

aLSO TAKE A LOOK at some more 'efficient' fans if you can cos some fans cost a fortune to run, compare output wattage on a few compared to yours.

Good luck dude, and post some pics when you get it sorted.