I saw a site reselling Premium WordPress themes released under GPL. This is legal but I am not convinced it is ethical. I strongly discourage anyone buying from such resellers or venturing into such business model.
Why should you buy from the original theme designers?
Buying from the original theme designers gives you not just the theme but access to support forums, knowledgebase, tutorials and theme documentation. I have found these resources invaluable and saves you loads of time spent in understanding and customizing the theme. I am also guaranteed to get the latest version of all themes and instant access to new theme releases in future.
Premium WordPress theme designing is a small and growing community. The more we support it the more we can get from it. The success of the current GPL theme providers is very important to encourage more designers to release their themes under GPL.
Why you should not buy from resellers?
Theme resellers don’t respect the spirit of GPL but take unfair use of it. This is equivalent to leeching. They neither add any value to the theme nor do any work to deserve the money they charge. I am not naming the site here so as not to give it free advertising. Also, this may be just the first of many sites to come. The site I saw don’t even have a name / face. What is the guarantee that they will stay for long?
Cheap resellers / free download sites may host malware that can hurt your website and PC very badly.