I've got a Smart-UPS 1500VA LCD 230V at home, and we also have one at work, the batteries are not expensive so long as you don't buy genuine APC ones. I recently purchased two replacement batteries (it takes two batteries) for the works unit and they came to £53 from Allbateries.co.uk
At home I have a server, my modem, 16 port switch and my projector running off of it. The projector is currently off (standby) and run time is estimated at 123 minutes with a load of 9.1%. Unfortunately it doesn't report the load in Watts, at least not that I can find quickly, but the server draws 80w to 100w roughly, the switch 6w, not sure on what the router draws, and there is another bit of equipment which draws 8w.
My home UPS is 5 years old and I've never replaced the batteries, the works unit has had them replaced twice, these UPS's carry out self tests and set off an alarm when the batteries need replacing, which is really easy to do and can be done with the equipment still powered up.