I dont think many hosts off that much bandwidth with a plan your best bet would be to email there sales or support department and get a quote also you did not state how much physical space you need. I also suggest posting in the requests forum for some prices but do research before signing up and maybe checking how long they have been in biz along with testing there support to see what type of response time you get. Good luck.
Yes, a dedicated server might work out better for you. A lot of companies offer the shared hosting with that much space if not more . . . But for the bandwidth that you are looking for, you would be better off finding a dedicated host.