Thanks for asking Question! The minimum Plan for Web App for Container (Windows) is Premium Container PC2 and Dev/Test pricing tiers are not available for this configuration. Product group is exploring this but no dates planned at this point of time.
You may refer to below link for Pricing Details:
https://azure.microsoft.com/en-in/pricing/details/app-service/windows/
Also, Windows containers are billed at a 50% discount while in preview.
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