It has happened to me on more than one occasion. Twice to be exact. I contact a potential buyer with an offer on a domain name. They reply with a counter offer, "I'll give you $x. " Maybe some additional negotiations take place, maybe not. At the end of the day, the potential buyer has made a counter offer. When I reply and accept that offer, the deal is binding.
Apparently, there are some business people that do not understand this element of contract law. They make a counter offer with little or no intention of following through on the deal. Maybe they are practicing their negotiating skills on my time. Maybe they are just curious as to what my reaction to the offer will be. Regardless, they don't complete the deal.
What options do I have? Not many, really. The level of dollars involved in these offers are not high, so it's not worth pursuing legal action. Besides, I don't want to develop a reputation as a lawsuit happy, crazy man that others wont want to come near. It's really just frustrating more than anything. I considered adding a small reminder to my emails solicitations reminding "Acceptance of a counter offer represents a binding agreement." But I really don't want to encourage counter offers.
It may just be a couple of bad apples, and I happened to pick them off the tree. For now, I'll just accept the fact that this happens and focus on finding a serious buyer when it does.