Making gil is almost impossible on most servers

[Rein-Yagami]

Items that tend to sell better are HQ items used to turn in leves for lazy crafters seeking to pay their way to L50.

Or those of us who understand such things as "HQ item spiritbonds faster = Quicker generation of high lvl materia = much profit"

adding 1 low lvl materia to HQ items further increases spiritbond speed which inturn increases the rate of materia creation.

Materia will always sell, regardless~ even those element resist lvl1 materia will sell because they are cheap and you'd rather not waste a good materia on something you intend to convert tbh.