If you don't wanna buy them, that's up to you. But honestly they aren't so expensive anymore and if you calculate the light value against the little amount of gil spent and the time you save ... it's more than worth it.

Also dragon farm exists, you don't have to do reflect farming.

Maybe you don't want to hear that, but it's not the game which looks you out on one of the best light farms ... it's yourself.

I would suggest opening a 'Dragon Lightfarm Party' via the partyfinder option and then head in, it#s ez.