If you can't put the materia in yourself (because your crafters arent high enough in lvl) then don't bother (unless of course an fc member or so does it for you). You don't want to spend gil for that.

One thing about materia: getting materia back isn't always 100% and putting it in also isn't if you pentameld.

If you want just put the highest for a given stat into your gear once you hit "was an endgame level" gear. Not really usefull to put materia in if your items are < ilevel 130