Reasons why I don't like offering first
1) I offer too little. *no response, I recheck over and over waiting, still no response.
User never responds ever again, Ignore mode. I lose 30 mins of my time, from rechecking the status over and over, and user could of let me known, and save me my time. (Which I don't get, why not bargain with me, and offer a higher rate? Why is everyone so scared of doing this?)
2) I offer too much. *You jump at it immediately, I am like fuuuu

And out a bit.
3) I offer just right. *happens rarely.
This happens in real life a lot, Craigslist, etc, well at least to me.
Now since I made my point across

You start with the first offer
That's why I always believe the seller should offer first. It is his item, and he already has some idea of what he is looking for. If you watch the pawn shop shows on TV they will never make the first offer. They always make the seller offer first. I've figured it's pretty much for the same reasons you listed.
(Sorry, not meaning to hijack the thread with this, just a pet peeve of mine lol. So consider this a free bump of your thread!