add pricing note

Author: deeikele

articles/ai-foundry/how-to/upgrade-azure-openai.md

@@ -134,6 +134,12 @@ After upgrading from Azure OpenAI to Azure AI Foundry, you'll notice updates to
 
    Your project overview page includes your previous Azure OpenAI endpoint, and a new Azure AI Foundry endpoint. Foundry API and SDK grant access to the broader set of models and features including agent service.
 
+## Understanding pricing
+
+There are no pricing differences for existing Azure OpenAI functionality when upgrading to Azure AI Foundry—your current usage patterns and costs remain unchanged. However, Azure AI Foundry unlocks access to additional features such as expanded model catalogs, agent services, and evaluation tools, which may have their own pricing structures depending on the models and services used.
+
+For estimating costs of new features available in Azure AI Foundry, use the [Azure Pricing Calculator](pricing/calculator/).
+
 ## Roll back to Azure OpenAI
 
 In case you run into any issues, a roll back option is available. As prerequisite to roll back, you're required to delete any of the following configurations first: