I am in the IT disaster recovery business. My observation is that after you go above 25kw, the price point starts getting better with diesel. I did a search on ebay, thought I would share.
http://www.ebay.com/itm/like/132105255960?lpid=82&chn=ps&ul_noapp=true
Military surplus may be an option as well.
Be sure you have proper ventilation and heat dispersion (can be used to heat the house via water radiator heat exchange system.
I might have to look more into military surplus.
My dad buys all kinds of stuff at those sales.
I need to get a portable generator and a manual bus transfer installed. Power losses aren’t that frequent but when out, it’s a day minimum.