I'm not sure I've ever paid more than £30/$45 for a single item. The Wilderlands of High Fantasy box set was under £30 AIR, and amazing value at the price. I overpaid just under £28 for the Neverwinter Campaign Setting from amazon.co.uk pre-order, expecting another box set, and was left very unhappy when a hardback book arrived that should have been under £20. Gargantuan Black Dragon mini was £15.
Ironically, I've spent nearly £200 on single orders of minis - but that was for dozens & dozens of individual minis. I'll spend far more if I can choose exactly what I'm getting, as opposed to a manufacturer-chosen box.