I used to dread changing the blade on my rotary cutter. Then I bought the Olfa Quick Change and I love it!! No more fiddling around with the screws and getting wobbly blades. It was worth every penny. This one on Amazon says $9. I paid more than that but it was still worth every penny.
http://www.amazon.com/Olfa-Quick-Cha.../dp/B00168253A