Different brands / versions have different features... AuroraCoderz Basic is exactly what the name implies, basic. We'll have a feature filled version out soon. SDR3.11s has a lot more features, hence the price difference. You can check the features on the different brands websites (auroracoderz.com / scriptsdoneright.com). If AC Basic had the same number of features the price would be the same.
Also, some of the other brands you mention are mostly encrypted, this will make developing your site frustrating, you may want to ask the script provider directly how much of the script is open before you buy.
the sites do not state the differences please explain
also admin demo not working please help