This very true - for example *why* is the 1989 proof sovereign so expensive? Yes it has a one-off (and rather nice) design, but the mintage numbers are higher than some of the later proof sovereigns and the price is way more than the other one-off design years (2002, 2005 and now 2012). The reason - demand! People like the coin...  I can explain the demand for the 1989 coin a bit.When collecting sovererigns it falls into many different catergories ie people collect by monarch, by reverse, by obverse etc. So lots more people chasing it