overmelding is really cheap nowadays, someone might be unlucky but all in all it takes not much effort to put 5 tier III materia into an item

at 14.1 it was a real pain, but now ... just get a spiritbond party and spiritbond some item sets (takes 30-45 min per set and u'll get up to 11 mostly useful materia), beside that you can easy make your chocobo rank 10

by this way even overmelding 2 savage aim III into an item isnt a big deal