Reselling Blender is not necessarily illegal, in fact the GPL license specifically allows for reasonable media charges. This can be nice if you are bandwidth limited.
However, a lot of these sellers are basically scammers and leaches who do things like violate copyright or try to hide the fact that they are reselling Open Source software you could download for free.
This rotten nonsense has been going on for a long time. Here are Ton's thoughts on the matter:
( I pasted the whole thing below to give google another taste of it)
With the success of blender.org projects, and publishing all the exciting Blender releases, we're now being challenged by third parties who like to ride the waves and do business with Blender.
There's nothing wrong with that. In its very nature, GNU GPL is about freedom, the freedom not only to use and modify the sources, but also to distribute and resell our releases under another brand name.
Unfortunately we keep receiving concerned emails and forum postings from people who were worried about resellers renaming Blender on websites or using Ebay to sell Blender downloads.
3DMofun - shamelessly removing credits
The Chinese Blender community pointed us at 3DMofun, a company in China abusing Blender - claiming they made this software themselves, removing every Blender credit from the UI, not crediting Blender translations, images and DVD contents... all with the aim of getting government funding for 3D education.
Here's a full report of by the BlenderCN community about this.
Only the software download via their BBS (incomplete download) still has the original GPL credit and Blender names.
Apart from 'naming and shaming' we can't do much yet now... see below.
Visit the very supportive Chinese Blender community for more information, or help them!
3DMagix and IllusionMage, scam or open source leeches?
The companies IllusionMage and 3Dmagix resell via their websites Blender under their own name. Both websites are probably managed by the same person or company.
On their web pages they intentionally hide that the products are distributions of GNU GPL licensed software, and that the software is freely downloadable as well. More-over, even after contacting them several times, they don't remove copyrighted content from their websites. A lot of text and images have been copied from blender.org and random images - not even from blender - were copied from various CG websites.
Rebranding and re-distributing GNU GPL software is a key right. This doesn't give the right to then also rebrand the credits, claims and artwork as created with Blender.
The sad thing is especially that people are being lured in with the suggestion that this is a cracked version Autodesk 3D Max. Their customers probably feel too ashamed after purchasing this product to complain really...
But what can we do? Not much really... lawyers will be a waste of money on this. Best is as usual to just publicize this well. "Sunlight is the best disinfectant" as a U.S. Supreme Court judge once said.
Chairman Blender Foundation