Hey folks,
 
One of my friends accidentally stepped over my cable and damaged it while trying to take my potato chips, and damaged it. I can clearly hear static when the wiring is turned, and it often frustrates me when I'm trying to position the output cable the right way so that sound comes from both sides of my cans. I can afford an upgrade, but unfortunately my budget is <$100, and I haven't really tried any other cables to form my own opinion about what step I should take to improve sound. Is there a decent upgrade worth taking given my price range? Any help is appreciated, thanks!

Have you checked the for sale forums? I think the going rate for a cardas cable thats on the shorter end  is ~$100.
I'd definitely recommend the cardas its very thick and sturdy.  As far as an improvement in sound, I'm not totally sure.
For about half your budget you can get a canare cable which is thicker than the stock cable.  

There is a cool ALO hybrid 6 ft cable going for $170 bit that's probably out of your price range.

http://www.charlestoncablecompany.com/sennheiser.html
 
6 ft. length -- $90.00
10 ft. length -- $100.00
 

You could always just get another stock cable.

Just go to Sennheiser's website and order another stock cable; I bought one for the explicit purpose of having a back-up. Besides, if you liked the cable that came with your HD650s, it's not like this will change its sound (potentially for the worse). You're looking for Part Number 092885, it retails at $13.27 (USD).

spend the money on a stock cable and buy some pretty wrap for it.