Design and built a website

We are a small business based in France. We are looking to develop a website to bring together consultants in humanitarian aid and development field around the world with their respective employers. This web site will be in 5 languages. Around 20 pages to design. Need payment getaway systems and ability to share profile links on social media. Consultants will maintain their complete profile for free. Employers will use the search engine to locate the right consultant for the job. While the employers can maintain their accounts with us for free ( which is not visible to outsiders but only to us)to obtain the contact details of the consultant, employer will have to pay. We will need a back end to carry our market research, edit/add content of the website etc. We want a professional looking, clean website which can be accessed from desktops, laptops, tablets and smart phones even with a less powerful internet accesses. Two of the websites that has some of same functionalities and features as the one we are looking to design ; https://www.freelancer.com/ [login to view URL] We would like to know how much will a web site like this will cost? duration it will take to complete latest date of strat