From my understanding distributing it on bittorrent would be redistribution which is permitted under the GPL without limitation (however Trademarks etc could still be violated!) This is how projects like CentOS work - they remove the trademarks, rebuild and then redistribute - and this is perfectly legal.
The company themselves are under no obligation to release source code unless they distribute the software to you.
So your options are:
- Get it from someone else (who redistributes it under the GPL)
- Purchase the product from the company - they'll give you the source code
I would personally suggest the latter option because it supports companies that support the GPL!