When it comes to the high-priced website developers, they are going to have a reputation to back them. They are going to have a portfolio of professional websites they have created that are going to speak for their work. High-priced website designers are going to have people who could vouch for them as well as have a very strong web presence. This is the reason why they are going to be priced so expensively, because what you are really paying for is a degree of certainty, not necessarily superior quality.
Joomla and Mambo CMS have been developed by the same professionals of web design industry. So, they possess a lot of common features. For example similar code, system requirements, etc. At the same time new releases of Joomla will differ from Mambo. Having compared Joomla and Mambo CMS‘s you can notice that Joomla has more options, better security issues, regular updates, additional Built-in-Applications, etc.