Record values

I bought the new version of the Rare Record Guide yesterday. This is the 2008 edition, which some people might consider somewhat premature as we're not even into 2007 yet. Comparing record values between the new and old guides gives some indication of the state of the vinyl market. In general, rock and roll records have slipped a little in value (potential buyers are dying off I guess) although there are exceptions. Oh Julie by The Crescendos, for example has jumped from £60 to £110. I've no idea why.
Some 1960s pop releases, especially later ones, have disappeared altogether, while there have been modest increases in categories such as ska and girl groups. The biggest rises are in the areas of Northern Soul and Motown where, for the first time, DJ or demo copies are valued as well as standard releases. Suddenly I discover that a number of Tamla Motown and other demo singles in my collection are worth three figure sums, which makes up for some others that have declined in value.
There's a huge section in the guide on the records of Bob Dylan, which, like that on the Beatles, delves into the minutiae of matrix numbers, label design and so on giving different values for each. It will be a mind boggling task working out which particular version I have and, given that the values don't vary much, a fairly pointless one. Still, if I'm anorak enough to go through the Guide checking the values of every record in my collection no doubt I'm prepared to have a go.