Yes, the AZ-303 exam is worth it. After clearing the AZ-103 exam, you will get a Microsoft Azure Administrator certification. This certification boosts your profile and helps in getting a job as an Azure Solution Architect. It will cost $165 USD with additional taxes for the AZ-303. The exam pricing is not too high and the certification valid for 2 years.
If you are preparing for the AZ-303 Certification exam, check out this Azure Architect Training Course by Intellipaat.
Also, check out this video for more information