Update view-events-request-bin.md

Author: ddematheu2

articles/communication-services/how-tos/event-grid/view-events-request-bin.md

@@ -15,6 +15,8 @@ ms.service: azure-communication-services
 
 This document shows you how to validate that your Azure Communication Services resource sends events using Azure Event Grid viewer or RequestBin. 
 
+[!NOTE] Using Azure Event Grid incurs additional costs. For more information, see [Azure Event Grid pricing](https://azure.microsoft.com/pricing/details/event-grid/).
+
 ## Pre-requisites
 
 - An Azure account with an active subscription. [Create an account for free](https://azure.microsoft.com/free/?WT.mc_id=A261C142F).