Patient touch is worth using as the first quality increasing ability, that way you lose nothing on fail and get 2 stacks on success. Some people use it twice, or 3 times if the second time fails. I use to do this but it is somewhat risky and unless you are dependent on luck to reach 100% quality, it is much more reliable to only use it once.

Materia prices seem to be on the rise atm on adamantoise, idk about cactaur. I believe prices will continue to rise as more people acquire the new gear, so it's probably going to be expensive to meld at this point and in the near future, but it may be better to buy them now if you don't want to wait for prices to drop again. Alchemic prices are likely to go down, so if you need money for melds i would suggest you sell alchemics before the price plummets instead of getting yellow script gear. The yellow script gear is a waste at this point, I would not bother with any of it. The crafting gear market is pretty dry compared to what the battle gear market will be when new gear is added, prices will go down on crafter gear if there is a few hardcore crafters on your server. Better to sell yellow scripts and buy what you can not make yet imo.