I don't know how much should it be.
Could anybody help me?Thank you.
Now, on to your question.
I invite you (read the Charter) to provide general, non-identifying info, and we might be able to offer some guidance, such as age of site, number of IBLs, age of IBLs, size of site, traffic info, etc.
As a rule, PR alone is deemed an ephemeral source of value and therefore not weighted that much in setting value.
High PR that is accompanied by other compelling circumstances - such as the site being a true authority site that is extensively linked to by other authority sites in a valuable niche with evidence of significant traffic from legitimate sources - would result in a potentially very high value. However, the high PR would be incidental (and therefore authentic) to the other factors - such as valuable content, linking, etc.