Hey, this may be an easy one, or not--let's say I have a +1 sword, and want to make it a +3 sword. The way I calculate it, the +1 cost 2000 gp, and a +3 is 18000, so I would have to come up with 16000 gp. Is that right? I've also heard, no, you pay the whole 18000 gp, same as if it was a new...