According to my calculations, and to my love for percentages. I've just known some important to a guitarist:
Dear guitarist, if you don't have a capo, you're using around a 25% of your guitar.
So, for my part, I'll try to get one immediately.
You can also try one, before go to shop. Look how to build one, here: http://www.wikihow.com/Make-a-Capo-with-Office-Materials
In my case, it didn't work very good because I've got an acoustic guitar, but it was enough to make my decision.