I bought my APC 500VA UPS with Voltage Regulator 300w ra good for a mid-range SB rig. ganahan ko makadungog balik sa *click* sound sa VR, hasn't failed me pa.
In your case, I suggest palit ug 650VA APC UPS with VR, mga 5k, same price as a industrial 1000w quality AVR. or you can go with the latter if ganahan ka. Opinion lang bro. hehe