1. First choose the right cloud.
a. Sales Cloud
b. Service Cloud
c. Marketing Cloud
d. Experience Cloud
e. Commerce Cloud(B2B/B2C)
2. Learn about Editions for Sales and Service Clouds as they provide different features. Based on the Edition we choose, the price varies.
Note:
a. Price and Usage Limits(Storage, API Calls, etc) are based on number of licenses(Users). So, always have a buffer.
b. There are Add-Ons available for additional cost.