Many sellers on eBay list software without a transfer form. Without this official transfer, the buyer is technically not the legal owner of the software, and if the seller keeps a copy, they are in violation of the EULA (End User License Agreement).
To understand the pricing of CS6 today, one must understand the historical context. adobe illustrator cs6 prix
Since you can't buy it new, here is your realistic market value based on the current grey market or used market. Many sellers on eBay list software without a transfer form