I am a occasional seller. I handle Best Offers many different ways.
-If the item seems to be popular (lots of views fast, lots of watchers) I probably wont accept the best offer's unless they are only asking a few dollars off. I've been testing this lately with just waiting and it's been working out in my favor. For example, I had a N64 on ebay for $50. In less than 8 hours I had 6 best offers. The highest one being $40. I stuck to my guns and before 12 hours had passed someone bought it for the $50 I was asking.
-If the item is popular but it hangs around for a few weeks I will be WAY more willing to accept anywhere from 15-30% off. I usually respond to the Best Offers letting them know to try that price again in a week or two.
-If the item is not popular, after a few days of it being on the site you can get me down as far as 50% very quick. A lot of the odd ball stuff I put on there I only really want to make $5-10 on. You just have to ask.
As a collector first who occasionally sells on ebay I also check my best offers feedback to see if they are resellers or douche's. I usually won't accept best offers from resellers. Doesn't always work, the N64 I sold for $50 went to a ebay reseller who only seems to find the rarest of overpriced action figures, looks like they sell the clothes from their closet and resells N64's for 149.95!! Don't worry, they also lied and claimed it was for their nephew....but they have 4-5 listed on ebay so you do the math.
I also had an offer from a guy who's ebay profile said the following...
"I buy stuff on ebay and if the item is not exactly as described I give bad feedback."
I don't sell to dingle berries in life either.
I personally prefer my stuff to go to collectors who want it and not some ass just trying to make more cash off somethings thats popular at the moment.