i reckon cos there is such a mixture of northern,modern,funk..etc,and a mixture of geography,collectors,dj's (wanna be dj's) traders and dealers,that there is enough of this shit to see us all out! and naturally prices increase and decrease with demand and availabilitie as it does with most things! as for investment,unless you sell and walk away,you will just keep ploughing the cash back into more/others records,cos we all do it,and were all as daft as eachother!