How much can my org ACTUALLY expect to pay for Salesforce? (More details inside)

Trying to evaluate SF as a real option but also look past all the sales noise. We’re interested in Financial Services Cloud and 35-40 licenses. Here are my questions: 1. $250 pupm is a joke right? Does anyone actually pay that much? 2. Which add-ons are absolutely necessary? Is Salesforce Shield the standard, or is it not worth it? How much does a sandbox cost? 3. How can we best guesstimate the cost of having a Salesforce partner/consultant to help with implementation and ongoing support?

Thanks in advance.