Exide STAR 1625VA
I bought it recently for 9k or so.
Issue - For some reason, it says overload when trying to start the PC on battery mode of inverter, but turning the inverter off then on solves it (inverter is in UPS mode). For now have connected my old APC BX1100 to my PC which in turn gets powered by the inverter during power cut.
Battery - I gambled on Lithium ion battery from a small brand called Nsure (model - INTU+), cost like 18k or so for 100Ah.
Another thing to note is that, generally a 100Ah Lithium battery is considered to provide to same battery backup as a 150Ah Lead acid battery.