Hi Ty
Welcome to Microsoft Q&A Forum, thank you for posting your query here!
It will not double your storage cost in the secondary region, when you Enable CRR Here is the storage pricing—you were almost correct, around $300: Azure Backup Pricing
Please refer to the below link:
https://azure.microsoft.com/en-in/pricing/details/backup/ Feel free to reach out if you have any further questions or need additional information—I’m happy to assist!
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