I had the double click issue with my MX revolution (since upgraded to a Performance MX).
Here are a couple of topics I used to try and correct the issue myself -
http://www.overclockers.com/forums/showthread.php?t=594646
http://www.overclockers.com/mouse-clicking-troubles-diy-repair/
I did, when researching the issue a while ago, see someone was selling replacements for that little metal piece that bends out of shape, but don't recall where I saw it.
I also used a program called mousefix.exe while waiting for my new mouse when I ordered it. It worked great, but it was only for NT/2000/XP (I have XP) so not sure if there is one available for Win7-8
This is, of course, assuming your mouse is no longer under warranty. If it's within 3 years, contact Logitech directly. Even if it's after 3, they will usually give you a discount on a new mouse (if that's what you decide to do).