i am at loss here, i havent got any idea about a below 5k phone with loud ring volume… it would be better if you took your friend to the shop and checked out the phone there…
There are several options like SE K310,Nokia 6070 and Moto flip which are below or around 5..
You can try Motorola L6i, nut dont know about it’s loudness, but one think is that they hve very decent ringing volumes. It has FM, Camera etc. It is available for around 6k.
If you are looking for colour screen and FM, the Nokia 6020 is quite a nice option. If you do not need the FM feature but a white light will do, then Nokia 1108 rocks!!!