Greetings! I have gone through your description and also understood the functionality of twiends website. I am sorry to say but your proposed budget is very low as per your requirements. It includes, designing, coding, testing, admin panel, user panel etc and it required time and efforts. I can propose you cheap offer by using already available CMS like, WordPress etc but if you really want a best solution my price is for you. If you still want to go for cheap option for CMS, I can offer you WordPress for $ 700.
I am available for the discussion. Thanks