As one of the experts on the UK Roadshow demonstrated, questions of value get complicated. The same old desk or set of chairs has at least four values.
The lowest (this number is for the eyes of the tax collector) is probate value. Next, in theory more realistic, auction value. Double the auction value and you have what a dealer will ask, retail value. Finally, somewhere atop retail value, insurance value.
All four values can be rationalized as correct for their purpose.
Probate value assumes a seller under pressure ("Must sell to settle estate") and buyers unwilling to shell out for anything less than a bargain ("I'm not really into Hepplewhite").
Auction value must be correct because it reflects the market, but the auction market can be zany. Some items go for two or three times pre-sale estimates, others go unsold.
Retail value reflects the added worth of all the study, expertise and leg work that dealers provide their clients. At least that's what dealers say.
Insurance value seems the mirror image of probate value. Here, the potential buyer may be desperate to replace his missing Jasper Johns flag painting, but who wants to sell him one?