When you do loss power, are you typically talking days or hours of outage?
Do you want it just for the tank or for the house as well?
If you talking hours (and you're not running sophisticated electronics) just grab a cheapo from Harbor Feight for less than a hundred bucks. Just remember a small generator will require you to fill the fuel more often.
If you're talking days or want to power the house as well, you'll need to spend quite a bit more $. Big box stores will carry high wattage portable generators that will power pretty much your entire house and are very affordable. Hondas are great but they're gonna cost you over 3X the price