I have never owned Konis, but a friend has them and loves them. However, they are made for peak performance and you pay that price. Most (All?) Konis are adjustable so you pay for that feature as well.
Bilsteins are great, I just put four on my Suburban for towing - what a difference! It seems as though the price is regulated by Bilstein - I only found a $5 difference or so between ALL the web sites that sell Bilstein. Auto Zone sells them also. You pay tax, but no shipping.