For the most part, I'm selling fixed-priced items for what I'm selling them for, and they aren't so expensive that there is a lot of wiggle room on pricing. With rising silver costs, my inventory costs have gone up, but I haven't changed many of my prices...yet.
The one thing I'd consider doing best offer on is something that ebay doesn't let you use it on... store logos. At least those are the errors I got last month. I have finite costs with selling jewelry, but when the main cost is my time and creative energy, there are times when I'm open to negotiation. Oh well! No best offer for me, I guess.