DKNY in the Starbazaar

A few years ago, the average second-hand selling price for DKNY was around 20sd. Not too long ago the average price rose to 30sd, then 40sd, and now you'll be lucky to find items such as skirts, tops and shoes for under 50sd. Why exactly has the price risen so much?
Perhaps because as time goes on, collectors find pieces they've been looking for and don't sell them on, therefore the piece becomes rarer and the price rises. Also, people in general will pay more just because the item is old, especially new members.
So, what do you think about DKNY becoming rarer? Do you find that you're willing to pay more than you used to, or (like me) rarely buy DKNY items any more and want the old prices back?