I am a realtor, so I am with a lot of couples when they decide what to do. Generally, I find that countering is a good idea if you want to sell the house. Most people (buyers and sellers) will split the difference if the offer is relatively close. Sometimes it takes one or two counters before you get close enough to split the difference. But in this situation, if it is not important to you that the cabin sells, then you can just let him make the decision. If he asks you what you think, you can suggest a counter to keep the buyer interested. If you want this to be his decision, you can give your opinion once, and then let him decide. But answer his emails or call if they are about the cabin. There is usually only a 24 hour response time for offers, so this is no time to play hard to get.
