The only one? I see you must be very new to the FFXIII forum.

In case you aren't really done with FFXIII here are some tips:

Gil is hard to come by. The best you can do is farm PSICOM soldiers for Credit/Incentive Chips in areas that permit it. Otherwise, you'll have to wait until the end of the game to beat up some Adamantoise. Anything that says "can be sold for a premium" in the item description isn't really good for anything else.
You aren't meant to upgrade your weapons/accessories like crazy. Unless you're going for an achievement, focus on one or two weapons per character (weapons with an ability that's useful, like the Axis Blade). As for Accessories, I would wait until later in the game when you get the good ones. It's pretty pointless upgrading crap +100 HP bangles when you're going to have a +1500 HP bangle later on.

To go through the story, you don't need to upgrade at all, and you can get by easily on what little gil is given. You don't even need to grind (the caps and CP cost hikes are meant to discourage you from doing this). It's more about strategy than just overwhelming the enemy with force like you would with some previous entries.