****Agents argue with me that the value is what a prospective buyer and seller have negotiated the sale price to be, regardless of what comparable sales show. "It is what somebody is willing to pay for it" to quote a recent conversation. On the other hand, a lender will typically require closed comparable sales that bracket the subject's features and sale price from within the last 6 months. USPAP has it's own very clear definition.****
When someone says it's what "somebody is willing to pay for it" I always remind them that may be true if they are paying all cash or have cash to make up the difference. In markets like yours, if there are multiple offers, shortage of inventory, etc., then the buyers better have CASH ready, END OF STORY, if their buyers are expecting the bank to finance over what it's worth, then they shouldn't be putting in offers on properties.
The other way I explain it to them is like this. When you see a car auction on TV or when you go to the courthouse and people bid on houses, in both cases if people pay more than what it's worth because, "that's what they are willing to pay", the BIG difference is that they pay for it when they leave. They don't hand over a letter from a lender stating they are going to get financed. I also ask them to email me the 3 or 4 best CLOSED COMPS over the past 6 months that they think are the most similar and I remind them COMPS not just SALES.