I totally agree that decent materials cost money. There was a thread a couple of days ago about the Boden Ravello top, looking for cheaper alternatives. The boden one is 35% silk and viscose and with a code is usually £40. All the dupes were 100% polyester and £20-30. I'd rather have a natural material than polyester.
What I do resent is the many shops replacing natural materials for polyester and increasing their prices.
I wanted a new coat last winter. Trying to find one that wasn't polyester or with a low wool count was madness. M&S were advertising their "with wool" ranges, but they were nearly all 90% polyester 10% wool.