(Hey guys, with the use of alchemy at my disposal, I thought, why not repair stuff to get some gil)
For levels 1-5 the price is the same as the durability of the item.
6-10 it's 20% more
11-20 is 40% more than durability
21-40 75%
41-50 is twice as much as the durability.
Trust me, it'll get expensive when you ever get that high. ^^ And it's item level, not your level, tho I think you can only have items as high as your own level.