It's difficult to make a recommendation without more information. The datasheets list the min/max power requirements of the devices, for example the MX68 requires 10-79 watts, and the MS210-48LP requires 53-490 watts (it's going to vary a lot depending on what and how many PoE devices are connected.) I would typically plan for the worst case scenario and size the UPS for a load of 600 watts, which would mean a minimum of a 1000VA UPS. That would give you a few minutes runtime at full load. Actual runtime would vary depending on the load.
I don't know what would be available at your local appliance store, but I have personally used APC, TrippLite, and CyberPower UPS units and had good luck with all of them. APC has a UPS Selector tool that will allow you to enter in the load in watts and the desired runtime in minutes, when I put in 600 watts and 10 minutes, it recommended a SmartUPS 1500 which would provide 14 minutes of runtime at 600 watts.
