The reason that Luvs diapers are cheaper than Pampers is that the Luvs diapers are a cheaper version of Pampers diapers.
Luvs diapers and Pampers diapers are made by the same company and are almost the same diaper but the Pampers are usually higher quality and more absorbent than Luvs diapers are.
Luvs and Pampers diapers are made by Procter and Gamble who manufactures other things and not just diapers.
I have a 7 year old brother who wears Luvs diapers both day and night and they fit him just fine.
My 7 year old brother has bed wetting issues as well as bladder issues where he cannot hold his pee in too long or he'll wet his pants.
So he wears Luvs size 7 diapers all the time to school and at home or wherever we go.
He tries to make it to the toilet when he can but other times he just pees in the diaper.
He goes through about 3 of the Luvs diapers per day and they hold quite a bit.
Luvs diapers do have a baby powder smell to them and you can easily tell he's wearing a Luvs diaper if you're near him.