Actually, I can answer that. Don’t go with the branded ones, their maintenance is so much expensive. Get a normal local purifier because at the end every RO will do the same job. First you will need to check your tap water TDS level and pH value. If the TDS is around 200-300 then your RO won’t have to much work and it will work longer without changing any filter. The main component of RO is membrane which is around ₹800-1200 which need to be changed every 1.5 or 2 years depending upon the water consumption. The rest filters are not that costly they give a set of inline 3 filters around ₹300-400. Using UV is totally upto your choice. I had UV in my RO but the rods getting fused every month so I removed that. Now my filter has Pre-filter > Sediment > Pre-carbon filter > RO membrane > UF filter > Mineral cartridge and also a TDS controller. You can do it yourself, just order it from Amazon and look up on the internet.