Like the others have said, it's quite costly to only level one craft especially if you don't plan on levelling any gatherers. Crafting for some May seem like a long boring task but it's really worth doing if you're levelling all, can make quite a bit of Gil just off levelling, take advantage of your daily leve allowances if you decide to level crafts it makes things a lot quicker. There's guides you can look up online, look for repeatable leves