Based on the search results, the starting price of a Bluetooth calling smartwatch during the Amazon Great Indian Festival is not explicitly mentioned. However, there are several deals and discounts available on smartwatches during the festival. Some of the smartwatches available during the festival include:

• Fire-Boltt Phoenix Pro 1.39 inch Bluetooth Calling Smartwatch with AI Voice Assistant, Metal Body with 120+ Sports Modes, SpO2, Heart Rate
• Amazfit Pop 3S with a large 1.96-inch AMOLED display, Bluetooth calling, and AI voice assistance features
• Realme Buds Wireless 3 with features like Bluetooth calling, sports modes, and a health tracker

It is recommended to check the Amazon website or app during the festival to find the starting price of a Bluetooth calling smartwatch and to take advantage of the available deals and discounts.