I have been having a hard time finding an answer to this anywhere. I know the licensing model has changed from SharePoint 2010 to 2013.
If we already have SharePoint 2010 licenses for our servers and users. We are planning a SharePoint 2013 upgrade, do any vendors allow you to potentially upgrade the SharePoint 2010 licenses (for potentially cheaper than new licenses) or do I have to completely purchase all new licenses for the 2013 server/users?
I dont think you will get any discount( may be check with vendors) but as per my experince you have to purchase full price new license what evertype you buy.
You can get estimate from this link.
Read this blog, explain and also give you pricing change overview.
Check with your service provider or Networking team , if you have " open licenses" then you have free upgrade to next version, but there are a few exceptions , the most important being SQL Server
