If you want it from Finland, huuto.net is your best bet. Otherwhise you have eBay, Amazon..

I was about to put my MX500 on eBay! It is used but still in very good shape. I can send you a few pictures if needed.

you can reach me: staubin.eric@gmail.com
I'm from Canada,Quebec

Tracking is simply superb. It would hurt me to sell it eheh

why do you need it? buy mx518
If you think that mx500 outperforms any other mouse at low sens after reading sujoy's review you are completely wrong. Actually mx518 has absolutely the same perfomance running at 400dpi/125hz as the mx500 running at 500/1000hz. Sujoy made a mistake testing every mouse on default DPI while mx518 is worse at default 800dpi ;)
+ you don't have to get out the additional weight
+ don't have to overclock the usb at LAN
+ don't have problems with tracking on some surfaces unlike as if you'd have bought mx500