^^ available locally at Ace/ Handyman but would cost higher.
Try Quiapo-Raon and Elfo-santa cruz they cost around 400-900 depending on brand just be wary about imitation panasonic brands. Some Motolite and Outlast stores carry also VRLA batteries. APC service center also sell this batteries.

UPS commonly uses 12V, capacity based from Amper-hour rating. BTW KVA is the apparent power which is converted to Watts(DC) by multiplying 0.6(common power factor).