Instead of bartering for fuses to complete puzzles, use the following trick. After completing the first fuse puzzle, return to the puzzle and collect all of the fuses. These will remain in your inventory, ready for use for other puzzles.
Replenish Your Gun Clip
Here's a great way to get more bullets for your gun clip without having to spend much money. If you've used up all of your bullets, or some (or most) of them, and you want to replenish your supply, simply do the following. Find a character who is trading gun clips, and swap your old, somewhat or completely used one for a new, completely replenished one.