Generally speaking, there are two ways to charge. The first is keywords, which depends on the popularity of keywords, such as how many search results there are and how many search times there are. The second is the optimization of the whole station.
You can ask any company about the specific charge, which is generally around 5000- 100000.
There may be something wrong with your idea. First of all, your product needs to be famous, and the website will have traffic. For example, last year, we asked Shangyi PR to do online promotion to let everyone know about your products, and then do seo, so that your website will be valuable.