Player asked for a bonus to his Paladin Aura range

5th edition game. I have a player who's started a new character as a paladin, we're level 9 right now and he has been asking me about gaining a magic item or feat of some kind that would set his paladin aura at 15 feet instead of 10 as an in between buff since paladin's don't gain more range until level 18.

My question is how powerful would this really be? It doesn't sound like much to me honestly and he wouldn't be gaining it until level 12-ish when the players are already pretty capable. However I would think there's a reason there aren't any items that do this and this player, as much as I like him, does tend to power game a lot. He has a tendency to really downplay anything character's are capable and can never be too strong, so he asks for things and has to be told no a lot.

I'm just wondering if I'm also downplaying an extra 5 foot on his aura radius or if extending the radius of paladin's is a bad idea since aura's are already strong.