I'll be moving to the Caribbean for a few months and taking my iMac with me, and there are daily power outages there. The building I'm staying in has backup generators but they take 10-15 seconds to kick in. I'm looking for a cheap UPS that will withstand those 10-15 seconds so my power supply doesn't fry. I've read several threads about how "pure sino wave" UPS's are the way to go for newer iMacs, but I haven't found one under $100 and many reviews indicate they're able to get 45-60 minutes on various UPS's in the $100-150 range. Since all I need is 30-60 seconds, that all seems like overkill for me. Any suggestions would be appreciated.