The cycler and PF together have a load of 600VA. There UPS Selectors from various manufacturers that allow you to plug in the load factor and time you want and it will recommend the appropriate UPS.
For example: http://www.apc.com/tools/ups_selector/index.cfm
Also, Google this for what may be a good deal on a backup for less than $300.
Xantrex-Technologies-Powerpack-500-Watt-802-1500