Ryzen 3600 was recently available for INR 5300 from amazon in last sale. Even now its around 6.7k after card discounts. In used market sellers are expecting 5-5.5k for OOW ~4 year old processor which doesn't make sense.
I suggest you to wait for upcoming festival sale, most probably the INR 5300 offer will come back but if you are in a hurry then better look for Ryzen 5600 in used market which sells for around 7-8k. Or if you can get a fairly priced Ryzen 3600 in used market (Around or under 4k if you ask me).