Blades add up! I recently tried out a blade sharpener, but I don't believe it works, so I will be returning it.
Meanwhile, while searching for something else on this board, I came across this website for exchanging rotary cutting blades:
http://www.lpsharp.com/3.html
Someone had posted about using them I believe. You can exchange your old blades for new Olfa blades for $3 each I think. There are other options as well.
I am thinking I want to try them out!