customised open source site??

Hello, I’m trying to make a website, and I need it cheap as possible, preferably using open source software where possible. Suggestions from developers are very welcome. I’m trying to make an online marketing website. I’d like media upload – so sort of images and videos. I’d like them to be compressed as much as possible without quality loss. I’ve got an AJAX based live search bar script, and would like that implemented. I’d also like additional search functions, which are readily available in open source. I want the site to have a ‘featured’ and ‘latest’ section, and these functions are freely available in software such as PHPMotion. I also want a subscription system, to control which users can view, or publish content. I’d like this to be self contained, meaning a user doesn’t have to leave the site to pay. There are newsletter functions available freely in Joomla extensions, and would like that also. For authors, I’d like a system where they can edit and view their listings. I want to include other features such as Google Maps, available in the API programme. For the different types of listings, I’d them to be stored in 3 mutually exclusive databases depending on the type. For free user upload, I’d like admin to be able to approve content before publishing. I’d like a login system, as per Joomla basic or could use additional open source based extensions which may be more robust. Ideally this is a project I think for someone who can also design creative and nice looking sites, and can also customise open source. I have layouts ready to provide. The reason I want a developer is because whilst I do know the type of technology that could be used, I don't know how to customise it.