To power that much stuff for a significant amount of time you're going to be spending a ton of money.
With that said, look into the CyberPower stuff. It's considered low budget but I've had great luck with them. I've got about 5 of their units. I forget what brand the rackmount ones I have are, but they seem to work pretty well too. However, I still don't get more than 15-20 mins of backup. The whole point of a ups is to allow you time to save your work and safely shut it down, not really to leave it running, unless you want to get into some custom systems which are $$$$$. If I remember correctly the UPS system they had installed for the datacenter I was working at in Georgia was around $500,000, but it powered the entire datacenter
