Renderings/Design of a virtual platform

Hi there, I am looking to design a virtual event space, probably a big green woodland space with three areas inside, a stage area, a dome or a tent and a wooden room, this will be a "world" for use on an online event platform like vfair.com. The Requirements for 3D graphic/model: JPEG or PNG format aspect ratio of your panorama in pixel width and height is 2:1 Example sizes of panoramas that will be treated as spherical: 6000x3000, 10000x5000 can you let me know some costs and a timeline thank you