State of the vinyl market

I've just bought the 2012 Rare Record Price Guide - and suddenly I'm several hundred pounds poorer. Compared with the previous edition (2010) prices of many of the vinyl records in my collection have fallen. Rock and roll and fifties LPs and singles have been declining for several years and the latest edition shows a continuation of this trend - particularly singles. Indeed, quite a few have disappeared from the guide altogether as they no longer reach the minimum value required for inclusion. I suppose it's the inevitability of age, as my generation retires or begins to die off.
Quite a lot of sixties soul records have reduced in value it seems, although Tamla Motown and Northern Soul rarities have resisted that trend. Ska has stayed rock steady in value and so has most UK sixties beat, but prog rock, psychedelic, Krautrock, British jazz and rare folk and acid folk albums have increased in value, along with perennial favourites such as the Beatles and the Stones. I tend to sell this type of record on Ebay as soon as I find it (in car boot sale, charity shop etc) and have done quite well recently, but the basis of my collection has suffered. The biggest rise of any record in my collection is an LP called Into Your Ears by Pete Dello and Friends, the value of which has leapt from £200 to £500. I bought it a few years back at a boot sale and I've hung on to it as an investment - and it seems to have paid off. The rare High Numbers (The Who) Fontana 45 Zoot Suit (pictured) has also increased and is now my rarest record at £600 (in mint condition which unfortunately it isn't). http://www.youtube.com/watch?v=-INQ63rnpLQ
Sadly, these increases have been more than outweighed by cuts in the values of records by the likes of Jerry Lee Lewis, Little Richard, various doowop groups and sixties soul stuff by Wilson Pickett and the like. And it's this type of vinyl that makes up most of my collection.
Never mind. It's the music that counts, not its value. I've recently sold LPs by Hendrix, Farirport Convention, Jethro Tull and Soft Machine - all for good prices. But, frankly, they have no place in my collection so I'm glad to have the cash.