This information you can get from FSB software review page for Skype for Business:
Skype for Business pricing is included in Microsoft Office 365, which offers three plans: Business Essentials ($6/user/month), Business ($10/user/month), and Business Premium ($15/user/month). The main differences between the plans include email hosting and video conferencing for up to 250 people.
You can purchase it if you start from here: https://www.skype.com/en/business/
Disclaimer: We spend hours researching and writing our articles and strive to provide accurate, up-to-date content. However, our research is meant to aid your own, and we are not acting as licensed professionals. We recommend that you consult with your own lawyer, accountant, or other licensed professional for relevant business decisions. Click here to see our full disclaimer.
Product or company names, logos, and trademarks referred to on this site belong to their respective owners.